Drupal Commerce: Calculating a shipping rate: Custom Shipping Price
It's probably easier to have multiple flat rates, and a conditional rule that the product for that price is in the cart.

Notes:


There's a commerce shipping rules module that has a "cart contains item" condition.
If you could get at the logic behind the prices you could deal with this more easily, like weight based or size based shipping. For hundreds of products it's unreasonable that there's no logic behind it outside of what they want to charge for shipping. What I could think of is a custom module using hook_commerce shipping method alter where the shipping method matched the shipping price in the field. I've written a small module that alters the shipping weight, but that again assumes logic the weight based shipping.