I don't know how are the legal aspects, but I think that give the ability to customers to pre-buy the product, or as kickstarter, do a simbolyc investment. Eg.

I don't know how are the legal aspects, but I think that give the ability to customers to pre-buy the product, or as kickstarter, do a simbolyc investment. Eg. $10 for thank in the honor page and a t-shirt.