The ones I've seen on the line at EG are pretty much custom or do-it-youself.  If you make one up of any decent hardwood and fit it to your barrel/action there are several stock duplicators who can use your creation as a pattern to make one out of any wood you can afford.  I imagine some of the big wide beaver tail type forends the factory put on the varmint rifles might have enough wood to reshape.  Don't know if Ruger sells replacements.

Dont worry too much about looks.  Many rifles you see at EG including some of the ones used by the "top shots" are very painfully obviously works in progress.  Yeah there are some nice fancy ones, and some really prime originals on the line too but the schuetzenmeister doesn't award any "style points".

For what its worth we are working on an article or series of articles about the various Ruger #1/3 that have been "on the line" or "on the tables" at EG.  It'll probably be out late Summer/early Fall if all goes well