I think I already answered this on another forum, but yes they are rare and price is somewhat relative given who the seller and buyer are. It's estimated there were about 75 non-prefix rilfles made in this caliber/configuration. Not as rare as a lot of other non-prefix No. Ones, but rarer than most. If it were in any other configuratoin than the 1B, it would be really rare and certainly worth close to the asking price.
If you plan to hold onto it a while, then $1800 may prove a good price, but only time will tell.

A 6mm in anything other than a 1B is extremely rare. The 1B 6mm is not all that common, but with an estimated 460 produced, it's not as rare as many others.
Here;s a link to an article by Lee Newton on his website (You need to Login or Register to view media files and links) . Lee is one of a handful of true experts on the No. 1 in this country. I only have 37 of these things........

Mike,
We No. 1 loonies hang out at the Yahoo Ruger No. 1 group (you have to join to view posts) and the RugerForum.com. There is also information on the 24 hour Campfire site and at Rugerforum.net.

The link I posted above has lots of information on the early, non-prefix guns. A recent reprint of Joe Clayton's No. 1 book also is invaluable for anyone interested in these rifles, and it contains information on the the later, rare s/n prefixed guns. And Chad Hiddleson's Ruger guide for members of the Red Eagle News Exhcange is worth it's weight in 25-20 SS brass.

At this point, there are probably as many rare post-1970 guns as there are non-prefixed ones, depending on how much a purist you are.
Of course, Ruger will never divulge production numbers and their chronological use of serial numbered receivers can be haphazard, so produciton estimates will always remain well-educated guesses based on years of collecting, discussion and research.

So, what is it that you have?
LC

I own what may be the rarest #1, one of the Lyman-Ruger 1878 Centennial rifles.  They have the only Ruger rifle shipped in a walnut case, the only #1 with a 28" round tapered barrel, the only #1 with a full length 4X scope (external adjustments), with reloading dies (all were 45-70) and some accessories.
The total number produced may not be as rare, but the number of unique accessories makes it special.

Rich

Perhaps off topic but sounds like the OP already got great information so with the staging already set up here is my question. Why oh why did Bill Ruger refuse to chamber his #1’s in 444 Marlin ? Talk about a natural pairing and yet he refused. Warren Center and Jim French of Thompson Contender Arms once said that Ruger didn’t get along with both Marlin’s management or DeHaas but never confirmed. Nevertheless a curious subject. 

Rick

I have had two Ruger #1's in 7x57 and a 77 in the same caliber. The chambers were a mess and fired case necks expanded .020 from loaded diameter.Case life was short but accuracy "OK".