I just recently got some 25mm wide, 50mm clincher rims from http://www.ebay.com/usr/speedcarbon11 for about $330. They've been very solid, although I don't use them on any hills remotely resembling steep and/or twisty.

I also have some 23mm wide, 50mm tubular rims from http://www.ebay.com/usr/a_baygoods for about $250. I use them mostly during criterium races (about 35+ miles per week, from January through August for the past two years). I also have a set of 88mm tubular rims by the same seller.

Both sets have been solid with no problems of any kind (other than finding quiet brakepads), but I think it's due to the superb build-job done by my local mechanic. I also don't for a minute think that the eBay seller will stand behind their products should something happen, and as a result, I probably won't even waste my time trying should something happen.

And, FWIW, I'm a 250-lb clydesdale. I run 32-spokes in the rear with 28 up front on both wheelsets.

If I feel the need for another pair, I might try the farsports mentioned by gc3, just to try.