HOLY COW, Rajas!
A magician could create an entire custom deck with gaffs, stripped/shortened edges, etc. and it would be affordable to make just a single copy for his own use!!
Is there a commitment to purchase more, or can someone simply create a single copy of a deck and that's it? There are some people who would definitely want to take advantage of such a service for the purpose of just making one unique deck for themselves!
Another question: the USPC offers small-run "personalized" decks - basically a photo back and standard faces for about $25 a pack. Would you be able to make such decks in short runs? At what price per unit and what volume? They're very popular for special occasions like weddings, company events, etc.
Another thought has popped into my head! I've been wanting for a long time to create a custom business card designed to look like a playing card. The service is available from USPC for the Rider and Mandolin Back Bicycle decks, but it's NOT cheap. Is this a service you could offer? If the prices are comparable to what you're offering for the custom prototype, it could be very competitive, indeed!
Lastly, let's say that someone wants to make a business-card or special-occasion deck, but has no design experience. Would you be able to assist with in-house design to create something the customer would like - and if so, at what cost?