I second the ASW 15 suggestion. Pros - They can be had for much less
than 20K, have good (but not great) performance. Easy to rig. My wings
go on much easier than most gliders I've seen. Roomy/comfortable
cockpit.

Cons - Check the cockpit payload on any you might look at. If you're
above average size you might be over max gross. The B model has a
higher max gross. Canopy does not have a hinge, it comes off
completely. Its a minor annoyance. Controls are not auto hook ups. For
some that's a deal breaker. I don't see it as a big thing. Safety
them, check them and check them again. Some have an off center tow
hook that can be an issue in a crosswind takeoff. Mine has a more
forward centerline release. They have an all-flying tail that some
people seem to not like. I don't know why. From what I've read,
twitchy pitch control on all flying tails is mostly a myth. There may
be some issue at high speeds but I rarely go more than 75-80 kts (like
I said - good but not great performance) I can't tell the difference
but I've never flown any other glass single seat glider.

Reading the above it may seem like more cons than pros but the cons
are mostly non-issues, in my opinion. Of course, its a biased opinion
since a 15 is what I own. In the "bang for the buck" category the ASW
15 and Libelle are hard to beat. If you have another $5-10K or go
partners the possibilities really open up.