I am working on tweaking a cart install and I am not sure how to proceed with a pricing model we want to use. Any help or ideas would be greatly appreciated. I am a programmer and do know PHP, so I can handle some advanced suggestions...

What I am trying to do is use a volume pricing model, which I know how to do using the Product Price Manager, but there is another requirement. It should use the history of the customer to determine the price per unit.

For instance, if I setup the pricing scheme as follows:
1-5 items is $10 each
6-10 items is $8 each
11+ items is $6 each

A customer comes in, completes a transaction for 4 items. These items are charged $10 each (no problem here). Now, the next time the customer logs in and buys 4 more of this same item, it should use the fact that they purchased 4 items previously to determine that their per item price in this transaction should be $8 each (4 previous + 4 this time). And so on....

As I said, I will accept any suggestions or ideas as well. I have the ability to store this total number of previous purchases of an item in a 3rd party system and read it from ZC, so if I just knew where to override the discounting stuff, I might be able to work from there.

Thanks in advance!