Be most wary of the Muzzlelite bullpup stocks. Unless you try one in person and like it, I'd definitely pass.
I'm as fascinated by bullpups as the next guy, but the Muzzlelite was flimsy, and had unquestionably the worst trigger pull I have ever experienced on a firearm, squirtgun, capgun, or fire extinguisher.
But on the opposite end of the 10/22 price/quality spectrum:
SpaceCowboy is referring to Ironwood Designs.
For those of you concerned, it's about $500 for the AUG, $1K for the WA2000.
http://www.ironwooddesigns.com/2aprod/1products.html
At first those sounded a bit high to me, but heck, compared to the other projects people spend money on, it's not half bad if you get a really high-quality bullpup out of it. Folks are drooling to spend $1200 on a .223 AUG, folks who don't compete routinely drop $400 on a semi-decent scope.
Considering how much use a frequent shooter gets out of a good .22LR, that's not too darn bad. I'm in gradschool right now, but haven't ruled out getting myself a little something special if I pick up a good job out of school...