I've created a bitcoin exchange/giftcard site (as part of it, I advised the owner of the risks related to accepting paypal and credit cards to receive funds which basically amount to if you accept this money and dont impose a minimum 45 day waiting period you're likely to go bankrupt);
I've also created a bitcoin casino, and done a bunch of crypto consulting and educational seminars. Funds deposited with the casino are held in escrow much like you want funds to be held for your project.
Since I have experience doing this sort of thing, and a record of advising clients against costly mistakes, I believe I am your best and least costly option.