Dealing with this at the moment, as I've got about 5 lifelong shooters estates colliding in my shop at the moment.

Selling the nice high end rifles is easy.  Selling the nicely sorted brass is easy.  New bullets in the original boxes, even incomplete is easy.  Scopes, reloading presses, bench rests, loading dies?  Easy.

Then, it gets into the hard to sell.  Reloaded ammo.  Who in their right mind will shoot it?  Yes, it can be broken down for components, at about 10 times more labor than the componetns are worth.

Remnant bullet lots:  I have a hard time with these.  Today, I went through a box full and came up with about 5 lots of 10 to 30 cast bullets in .32 cal.  Remnants of a shooters favorite or not so much so mold sessions.  Who wants odd lots enough to even pay postage?   It's painful, but they just need to go in the lead scrap pot to eventually become new casting metal.  

Here's the real hard part.  Some of these guys were accomplished machinists.  A box full of various sizing dies, custom made for ???  Bullet sizers.  Swaging dies.  Neck Sizers.  Small base problem solvers.  All unidentified.  What can a person do with these.  Not worth the time to puzzle out what they are, much less find a home for them.  

Springs from who knows what rifles, that were replaced with custom springs to somehow improve the triggers or actions.  Jars of irreplaceable spare rifle screws, not worth the time to sort and identify.  Extra sears, triggers, firing pins for ????.  Sights taken off a lifetime of rifles to put on scopes.   4 remnant RCBS or Lyman sizing die decapping pins, from a pack of 5 used to repair a die once.  

I hate to throw things away, but most of the time that's the only solution.  It's a curse to want to try find a meaningful home for everything.  

I get more .22 rimfire cheap ammo than I can ever shoot.  5 or 15 at a time, loose in almost every box, tote, drawer that has reloading stuff in it.  I use it for function testing stuff, and still end up with quart containers full of mixed ammo stockpiled for plinking and function testing.

Parts guns, takeoff barrels, old stocks.  A bit easier, most can be ebayed and at least found a home.  

Not asking for a solution, there's essentially not one that's worth the labor it takes.

This is something every one of us should sort out and take care of before our heirs have to.  At least make a sticky note and put it in a ziplock with the part or tool identifying what it is!

Food for thought.....

What's your user name on eBay, Dave?

I know what you mean. Right now I'm sitting on a couple of hundred reloads that I got in auction lots which I will not sell or give away. Tomorrow is Guy Fawkes night and I think that I'll toss them all into the bonfire. Should be fun.

Last estate I bought was a guy's entire reloading room and ammo storage. Not a single box of factory ammo, but a ton of reloaded ammo. 300 boxes of 12ga. ammo all in plain white boxes he bought. Only thing written on the boxes was the caliber and shot size. I sold them all at one gun show for $2 a box and two guys too 100 boxes each, then the rest went in 10 or 20 box sales. The only new ammo was .22LR and .22 Magnum, and I sold all the magnum, but kept the .22LR in new boxes for myself. 
Had over 500 rds. of .223 ammo in 20 rd. plastic MTM boxes. I sold them for $3 a box as I figured the plastic boxes were worth that. Then a bunch of .45ACP, .357, .38 Special, and some small amounts of other calibers. I sold 50 rd. boxes of reloaded pistol ammo for $5 a box in MTM boxes, and it all went quickly too.
Also had over 50 bamboo fly rods and a couple dozen fly reels. I sold the name brand rods for $100 each and the unknown for $30 each. All went at one gun show quickly.
Lots of reloading equipment that I sold at 20% of new prices to move it quickly. I did have a few items I kept like a new Bushnell spotting scope I gave my son inlaw for helping, and an early Swarovski spotting scope I kept for myself.  Lots of die sets, but also a bunch of individual dies that didn't make a set. I sold the common sets for $10 each and individual dies for $1 each. The unusual die sets I sold for $25 each, but still have a .22 Rem. Jet C&H set that nobody has ever wanted for $30.
I sold everything to friends and family first, and the rest at the gun show the next day. My old '69 Suburban was so full when I headed home that the rear springs were completely collapsed, and front end felt like it was barely touching the ground! I went 40 mph down the freeway slow lane the 8 miles home!

Back when I was still in Walla Walla managing the gun shop, we had an older fellow and his wife that came in quite frequently.

Unfortunately, he was suffering from dementia, and so he (she actually) was selling off a lifetime’s worth of firearms, accessories, and reloading equipment.

They brought in close to a 100 pounds or so of various powders, and that’s when the problems began. We found eight pound jugs of powder that had more than eight pounds inside, along with one pound jugs of the same powder that were partially empty. That set off immediate alarms, of course.

There were also relabeled jugs, powder in recycled coffee and food jars, even a paper sack of powder (I remember watching relatives buy powder in paper bags at gun shops, dipped up from huge canisters).

In the end, there were perhaps eight or ten pounds of powder in sealed containers. We explained the situation to the missus, and she immediately told us to dispose of the rest.

We wouldn’t accept any of his reloads for sale, because we couldn’t guarantee that buyers would break them down, so they got rid of all that by some means.

He mentioned having many, many molds, and we asked that those be brought in. A few days later he showed up, and was proud that he had sold them all to a local butcher. As you might imagine, he didn’t get ten cents on the dollar for them.

It was really sad to watch, as you could see that toll it was taking on the family.

I believe that ssdave is also ssdave on Gunbroker. (Looks like his stuff there.) 

I agree with what you said Jonathan but the devil is in the details . 
The internet has a wealth of information at your fingertips but it can be very misleading if you only have a superficial knowledge of the subject matter. Small details which a neophyte would never notice can make a world of difference. The knowledge required to give a reasonably accurate estimate of value requires many years of study and experience.
Just my two cents fwiw
Joe S

Then there's this fellow that came into a shop I used to frequent with an old, but new in the box Colt SAA.

He plunked it down on the counter, pulled out a receipt, unfolded it and put it on the counter and said:

"I know how you guys operate, want to buy a gun cheap, but I've got my receipt, and won't sell it for a penny less than I paid for it".  The shop owner looked at the receipt, and it was for $125.  He started to say "But, sir, this was the price in 1966.....".  The old fellow broke in with "I said, I won't take a penny less, you want to buy it or you want me to leave?"   

The owner pulled $125 out of the till, handed it to him and he left.  $1000 profit for the shop that day.  They would have paid $750 if he would have let them!