I've got a couple extra sets of 16/20 hole carbon rims. 38mm and 50mm deep, 23mm wide rims.
I have 2 sets of black tt c-4 hubs, $150pair, 1 set of red standard 16/20 c-4 hubs, $150/pair.
Also have some ultralight black (dati type) 255 gram for the set for $150, 16/20hole. Could build the 38s up at less than 1100 grams for less than $550.
Laser spokes or Cx-ray spokes are recommended. Aero advantages between these spokes. I've wandered about the aero advantage between the 2 spokes. Usually I do cx-ray if I am building less than 24 spokes, I figure if you are building a 28 or 32 hole wheel, you aren't too concerned about aero advantages anyway...but it if the chart is correct, you are only saving a watt or so going with the cx-ray...