I'm looking to replace the stock wheelset on my '07 Langster. Right now, they are Alex rims laced to anonymous hubs with anonymous spokes. They're relatively strong, but pig-heavy and the flex more than an narcacistic body builder in a house of mirrors, resulting an a loud, annoying clicking sound every time I hammer out of the saddle or hit a serious bump in the road as the rims and spokes flex.

Here's the kind of riding I do and the kind of wheels I'm looking for. Essentially, I'm looking for a source (catalogue, website, shop, back-alley dealer, etc...) for the kind of built-up wheels I'm looking for.

Riding:
Road riding, both long-distance commuting and high-performance road-riding (everything from one-hour interval rides to centuries). I don't ride fixed, just freewheel. Generally, I torque the hell out of my bike, sprinting on it and attacking hills out of the saddle, then bomb through downtown DC, then take it out on the open road for some nice, rural miles. No bike polo, alley-cats, or working skate parks on these, just the afformatnioned kinds of riding, basically, a roadie sans derailleurs.

Wheels:
since I don't know how to build them, I need to buy them pre-built. I need strong and stiff, able to resist lateral torque, but still aero and comfortable enough for the road. And of course, the lighter the better. Budget is around $300. I've heard mixed reviews about Velocity wheels, and I would be very interested in Mavic wheelsets (Open Pros, CXP 33s, but not Elipses). In general, though, since good pre-built singlespeed road wheels are hard to find and not very available, I'm open to all suggestions.

Thanks in advance for any help and advice.