Ubercart

I'm not the guy in charge of payment stuff, but that sounds like something we'd want for our own sites as well. It may be that your payment gateways aren't set up, but it may also be that it's just not implemented yet. Fortunately, Ryan's coming back on Monday, so we can bombard him with questions then.

I'm not sure how to do this the way you want it but here's a workaround with a lot less functionality and automation. I'm thinking about using the method i describe below until your method is implemented:

1) Create a product and call it "client payment"
2) make it a $1 product (sells for $1)
2b) possibly create an invoice number field on the product so that the customer can fill out an invoice number when they make a payment

3) print an invoice and send it to your client
4) they can log in and purchase x # of $1 products to pay on your invoice.

if your invoice is $500 and they purchase 250 units, they still owe you $250.
if they purchase 500 units, payment is in full

5) on the backend you unfortunately have to "manually" close out the invoices and keep track of payments. That's not optimal. But my method allows clients to make payments online and you to keep track of them in the backend.

NOTES: i imagine my method could be formalized to make it automated in code on the backend.

Also, reporting could be added so that you could generate reports on the invoice field i mentioned above and or client name to make the backend mgt easier. In fact, if this was done, it probably would make my method fairly easy to use.

Finally. Although i have NOT used my own method described above, i imagine it would work quite feasibly if you only generate a limited number of invoices a month. As the number of invoices / month goes up, then tracking teh payments becomes more difficult and prone to errors. That's when the module code comes into play.