In just some brief looking I did, I found some from $3100 to about $3900 price range. It wouldn't be a steal, but if there's anything that's been done to the bike for mods....sounds like a decent deal to me if it's in good condition.
Not a great price, but not bad. 20K is not a lot of miles- I personally know a lot of folks who went 60-80K on them, and at least one that went 100K on one.
