Do you want a box rim or something more V like?

Open Pros are always a good bet. There's also DT's version, the 1.1. Aeroheads are decent and I like them myself.

If you want something more V like I'd recommend IRD Cadence Aero rims. 30mm deep, 455g, only come in machined black but good rim.

Be sure to build with double butted spokes. I'd say Sapim Lasers or DT Revolutions up front and whatever you want on the rear.

Using Formula hubs will keep the costs down.