Another solution to your problem of people backing out would be to just make people who want one pay the full price up front, and charge a "restocking fee" or some such if they pull out (possibly put in a cut off date, since you don't order components for the pf's right away).
If you only want people who are 100% on the pf and the title, that's how you do it. CPR is past the point of getting their name out and getting their products out (as proof of quality), there is no reason for this method, just let the customers who want the product pay the money for the product. You know you'll make the PF, it's just a matter of when. Now you are saying 12-18 months, so the customer knows they have to wait at least a year for their product. It will make them think it over before just dropping the cash down.