I had a similar experience with my wife's 1998 Jimmy. Fuel sender went out (in-tank type). Dealer wanted $560 for the PARTS ALONE. Well, that idea was out! My parts source wanted $360 for the part also. That idea was out as well.
Believe it or not, I found the exact AC Delco replacement unit from a guy in California on Ebay for $175 shipped!! I did a "buy in now" and had him Fedex me the part. I drained and dropped the tank on the Jimmy, installed the new pump/sender and was back on the road the same day. $175 and my time to do the work (with the wifes help)! If you have some mechanical ability, I would say you could probably DIY if you can get the part at a decent price. Just my opinion. Andy