The choice for ~50mm carbon clinchers for less than $1200 is limited to the Williams, Soul, Neuvation and Spinnergy.
Possibly a set of FFWD wheels but I don't know how much they cost in the US. I've seen them for about 1000 Euro
I have a set of Spinnergy Stealth PBO FCC that I got for ~1100 from Kim's bikes off of eBay.
They are very smooth riding wheels.
http://www.spinergy.com/Bicycle/stealthFCC.html