Create unique products that can be ordered once
A hard one:
A clients needs a shop that sells unique products. Every product is sold only hundred times and the client can choose the number (1-100) that he/she gets. The selected number will be printed on the product and cannot be sold twice.
So a client should be able to select a product, select a number out of a list of available numbers in that batch and pay. The selected number will be printed on the product and from now on, that number is not selectable anymore.
Any ideas on how to achieve this?