I don't mean to be rude, just boldly honest. I hope this doesn't come off negative but helpfully objective.
I wouldn't really want to buy a Sculpey BJD for $100+ when I could get a resin one in the same size (Or tinies which are smaller) for around the same price with changeable eyes, hair and so on. I'd enjoy seeing your progress though and be curious about what you'd make, but I personally would be too afraid of the sculpey cracking, breaking, chipping, or warping. It's not a very stable material, especially if strung with something that'd rub against the clay and wear away at the surface inside. But I think it'd be a fun thing to offer at conventions... however to the average con goer $100 is a lot to drop into something that's 1/6 size. (Not that I wouldn't, I own plenty BJD as it is, but generally speaking.) The majority of Con-goers won't understand the work that goes into your dolls, and aren't really very Doll-savy in general, so the price would shock them considerably.
How would wig's cost you so much? Are you hand-making/sewing the caps using wig wefts yourself? There are purchasable 1/6 wigs both from Volks and from other Bjd dealers such as Junkyspot as well as Ebay, and the yretail from $5-15 or so per wig. So I'm curious about that.