I am curious because I'm not too far from you and keep a pretty keen eye on the bikes in this area.
I agree with the others, this bike looks like it's been rode hard and hung up wet. And with 20,000 on the odometer, and it's year, I would start looking at how available parts are for it, because it's gonna need some.
I have a 93 KLX650 that parts are nearly non-existent, and have learned my lesson there.
I would offer $650.00 if it runs, and go from there.
I cant see it being worth more than $850.00 though in it's current condition, unless it runs super-strong, and comes with extra stuff.
But even then, it's still 23+ years old, and when it breaks, can you get parts for it?
Edit: it books (trade-in) for $995.00 in good condition. See below;
http://www.kbb.com/motorcycles/suzuki/dr650s/1993/?pricetype=trade-in
Another good question is; are you capable of doing any repairs it might need by yourself?
If not, I would pass it by and look for something newer.