marketpress, restrict and calculate shipping for smaller regions?

I have a client that ships her products to her local city and the surrounding regions. Shipping to places within 50 kilometers is $10 flat. 75 kilometers is $15 flat, etc, etc.

Does anyone have a shipping api for Canadian postal codes / cities that might work? Or any suggestions? We're thinking of creating our own api but the budget and timeline doesn't allow us.

I'm going to look at the fedex api next to display pricing, the caveat is she uses a local shipping company to deliver her products.

Thanks in advance for comments and suggestions