I WAS TOLD BY MY AUTO SHOP THAT I NEEDED A NEW ...

Of course you can be expected to pay for the parts that are installed. Who else do you know who gives parts away or sells them to you for less than they paid for 'em? However, they must be awfully proud of those parts. I thought $450.00 installed for a pump for my mother's Grand Caravan was a lot. We all know GM parts cost way more than for most other brands but I think I'd call around to get a few other estimates. If $800.00 is out-of-line, have them put the old pump back in, pay them for their labor, and have it diagnosed somewhere else.

My other concern is why anyone thinks a fuel pump is the cause of "start-up issues". That doesn't really describe the symptoms. Does it have a long crank time before it starts? Runs rough when first started? Is the fuel pressure suspected of bleeding down overnight or has it even been tested?