Shipping from different locations

I am setting up a dropship site. My products ship from different locations across the US, to different locations across the US.
How can I make it that the shipping charges the customer sees are relative to the products location? Currently in UPS & USPS I can only enter one "ship from" zip code.

I have entered the originating zipcode of each product in the "Location" field.

Any advice? I am obviously not a developer, but I am working with one. I was hoping there was a simple answer that I can manage myself.
Thanks in advance for any assistance.

I'd like to know of a solution for this also, I'm using FedEx. Thanks.