We want to set up an open purchase order with the local hardware store and I'm trying to determine the best way to do this in X3.

Specifically, I want this to be amount-based, not quantity-based.

Let's say $1000.00 for a 3 month period using a Miscellaneous, non-stock "MISC-SUPPLIES" item. I don't care how many items they buy, what they buy, or how many times they make a purchase during that period of time.  I only want to control the spend amount during this period.  

The Purchasing > Open Orders functionality looks to be more for inventory items where we know item, qty, and price.

Does anyone have guidance (and maybe a screenshot or five)?

Glen