586 in 2 1/2" or the even rarer 3"? Big $$$...they don't show up often. There were some of each made in the mid 90's but not much. I was lucky enough to come across a 3" a while back and had it lettered...one of 108 in the run it came from. There was at least one other run but I would guess the total production at less than 400. There are probably more 2 1/2" but not a lot of those either!
I saw a 2 1/2" used and no box on GB lately that was nice but a shooter...the seller wanted too much and it didn't sell, seems like he wanted $1200 or so.
On the other hand you can find the 586 3" PC most of the time. It is a matte finish lock gun, very nice but at least $1K or more.
Good luck in your search and post if you come up with something.