i have a 77 vt in 243 - i set it up for 1000 yard f-class shooting for my daughter. she doesn't like it (she's 10 - so what does she know, anyway??) so it pulls long range target work for me, now.
i like the trigger and stock on it. i think the barrel is too light of a contour for a true varminter or target rifle, but it is serviceable. it doesn't hold a candle, accuracy wise, to my other 1000 yard guns, but it is accurate enough to play at 1000 and have a little fun. i hate the ruger scope mount system, and really wish they would have done something else for their vt-series (mine has a burris 'adapter' and burris weaver-style rings). i like 26" barrel, and the 9-twist has no problems stabilizing 105 grain hornady a-max bullets.
overall, i think it is a solid rifle that has some user-specific quirks.
i also think $625 is at least $100 over priced for a used 243 varminter. the 243 is a pretty hot cartridge, the ruger vt is heavy enough to shoot the 243 comfortably quite a bit. all that means that you may be buying a rifle that only has half its barrel life left.
good luck!