Bluegrass, you are correct in that these things are expensive, especially for what they are. I did a quick look and found one for 335! On eBay there is one for a few dollars less that the one you found but that included shipping.
Which one of your pumps failed, the one in the front, the one on the rear rail, or the one in the Hurricane bay?
If it was the one on the rear frame, you should reroute the hoses so that you can mount the pump with the motor on top. That way, if the seal leaks, coolant won't run into the motor.