20 spoke rims from QBP (the commonest parts catalog most any bike shop can order from...). last field on each line is the QBP catalog number.

DT Swiss RR585 - black - RM1843
Enve Composites - 45 Clincher - RM0540
Enve Composites - 68 Clincher - RM0560
H+Son - SL42 - black - RM4378
Zipp 111(101) - alloy - RM7951
Zipp X44 (303 Firecrest) - carbon - RM7953
Zipp X56... lots more Zipp's.

16 spoke rims...
can only find Zipp. see page 698 of the 2012 QBP Catalog.
http://viewer.zmags.com/publication/...#/a8e5bd2a/698


there's another consideration here. low spoke count wheels require VERY high spoke tension, and are not something the average bike shop is prepared to deal with. I know I sure wouldn't want to be replacing a 20 or 16 spoke rim.