1) Would a 3 1/2 foot tall, 3 foot wide, 3 1/2 foot long custom cage work?
Yeah, I'd say that'd work. Mine is 4 foot tall, 4 foot wide and 2 foot deep.
2) Do they need a moving water source like mountain horned dragons do?
No, but it doesn't hurt. Mine seem to respond better to moving water than to still water. Plus it adds a nice touch 
3) How much will a cb babie cost?
Probably 150 bucks, give or take. Probably a little bit more, but I've found some for 150. Be sure to get it from someone who actually knows. If the response is vague or "iffy", it's probably an import.
4) If wc what are the chances of parasites and/or disease for babies?
I have only had one wc baby, and it was clean. However, there's always a chance with wild caughts. Does 50/50 sound fair anyone?