Price option 1: Full price - product ships immediately.
Price option 2: 1/2 down - product ships when balance is paid
People that wanted to pay with two different credit cards would simply place a second order for the second half with a different credit card.
Well ... I'm selling conference registrations rather than a shipping product. So if people want to buy say 5 registrations, they can get a discount, but will probably want to pay with multiple credit cards because of the spending limits.
Nevertheless, I think there is merit in the idea. What I could perhaps do is force anyone who wants to purchase multiple registrations to become a "member", and then create a "group" by stipulating how many registrations they want to buy. I could then calculate a total price for that group, and auto-allocate each individual membership a product code that I put in the database. They could then "go shopping", and eCart could auto-create a series of Add-To-Cart buttons for each registration as a product. They could buy what they wanted on one card. When that has been paid for, the membership can be released, and the relevant amount deducted. Then when they are ready to purchase another set of registrations they go through the process again. Seems complicated and roundabout, but a group membership approach might work.
Thanks for the suggestion.
With every good wish,