You don't have to spend over $100 on a pump. The Melling Select pumps that I have mentioned before are only in the mid-$60 range.
Here's a list of all the Melling Select pumps on Jegs, I'm sure you'll find them all on Summit for a similar price if you look:
http://www.jegs.com/webapp/wcs/store...0002_751586_-1
Also, check to make sure that shaft will fit in a stock 400 block. Some of the aftermarket shafts require machining of the block before you can use them, and some don't.
- Justin