(hopefully it's alright to post craigslist links here--if not, sorry)
http://boston.craigslist.org/nos/mcy/3776843708.html
I'm a little surprised about a "DIY ignition advancer", and to be honest I don't know what that is.
$1900 seems a little steep for a 15-year-old GS, no?
But I would like another GS500...I had one back in the day and really liked it.
Thoughts?
Considering how it looks and the condition visible in the pics, I would guess asking $1900 will get this bike sold quickly. It doesn't appear to have any evidence in the pics that it's been dropped or abused.
The DIY ignition advancer can be found here http://wiki.gstwins.com/index.php?n=Upgrades.IgnitionAdvancer (http://wiki.gstwins.com/index.php?n=Upgrades.IgnitionAdvancer) so I don't think you'd need to be too worried about it.
See it/listen to it run, ride it, if all looks like in the pics and it behaves nicely, I'd be prepared to pay somewhere close to the asking price. Of course, I don't know what bikes are going for in the Boston area. Around here that would be a decent price this time of year. If at all possible, try to ensure seller doesn't have it warmed up when you see it so you can see how it starts when cold.