Customer has 100% Discount Free Shipping

[StunGun]

Zen Cart 13.9f
What I want to do is be able to track my stock orders by letting myself as a customer do purchases with 100% discount and Free shipping.
That is so I can order parts for my shop stock and have the Inv# to track what and when I have ordered for stock so when I check out there is no CC charge for parts or shipping. That way when I order parts from vendor I can put the inv# on that order to track it. And I also could update that order with my UPS tracking info when shipped from vender to me. Store runs good been up for 3 years 1000's of orders.
Is there a trick I have not found.

[mprough]

Send yourself a gift certificate....

~Melanie