since the 125 two strokes are pretty much obsolete you can find a 2002ish around 1 grand.
80’s will still bring some $ because a lot of kids still race them.
there is a guy who is selling a SDG 110cc pit bike on plesant rd in hamburg. he wants 1500 for it.
EDIT: you will have a TON more fun on a pitbike… read: ( klx 110 or honda crf50 modded)
They are much quieter and are a ton of fun on BMX trails.
as far as trail riding. there isn’t anywhere in WNY that is legal.