Some of the older 90's full suspension frames are collectable or very hard to find... I was looking for a proflex frame but the only one I saw that could accept motorizing easily is still selling for nearly $500, but well worth it. I was also looking for an older GT LTS frame but those are also really hard to find as just a frame, and will still cost around $200 for one in rebuildable condition. I guess I just got lucky to get that Specialized frame i just got for that price, but when I see stuff like this I have to jump on it if I got the funding because they sell so quickly...
Here's one I just found but it's up for bid if anyone's interested... a very nice GT LTS with about a day and a half remaining, the current bid is only about $27 right now but that's sure to go up when it comes closer to ending. I'm not going to bid on this one so if anyone wants a really nice dual suspension frame that's real easy to motorize, here's a chance to own one of the best motorizeable dual suspension frames... The seller is also including the Rock Shock so good luck bidding if anyone wants to try for it.... http://www.ebay.com/itm/OMG-RARE-GT-...3D261915582302
Here's that Proflex I've been keeping my eyes on... This one is still kinda pricy, but still a good deal since it comes with the Girvin/ Noleen front end that's worth around $200 alone... Just replace the worn out polymers with real springs or do like I did on mine and replace the front polymer with a go kart shock and a mountainbike spring.... http://www.ebay.com/itm/281551009412
These Proflex bikes with the open triangle frames are really hard to find complete enough to rebuild.