Which shopping cart stack for simple ecommerce solution

We want to automate the way we collect membership subscriptions. The amount is the same for everyone - there is only one price / one product. Multiple payment options might be useful but not essential. Customer needs to receive an auto-email with a unique membership number. Ideally there would be a pull down menu that displays the source of the membership - and this will be embedded into the unique membersip number. Is there a stack out there that will get me all or part way there? Thanks for your help!