In our site, we'd just need to configure a place where to sell numbers for a draw.

The only requirement is that stock of number of articles (concrete number in the draw) goes from 1 to 0 as soon as payment is confirmed, so none can buy repeated numbers.

Ofcourse we need to keep record of the user who bought every number, rather in a public way than private.

Would it be possible through your solution with osCommerce ??