What can I expect fuel pump repair to cost and etc.

I have an 09 Traverse. While away on a
work trip a coworker drove it and one
day they had an issue where it seemed
it lost some power and felt it would
die. They said it did that for cpl mins
and died cpl times on them. I found
out like 2 days later, when it happened
to me and one of the girls that it first
happened to. Probably next day after
acting find again we drive it 10.5hrs
straight back home, no issue. After we
come back I was with friends and
someone sat in it playing radio while
it's off, approx 30 mins. Struggled alot
to get it going and keeping it from
dying. Had to run few errands and kept
it idling for this, went home,  parked it
and next morning wouldn't start,
almost no power. After few mins no
power. Took battery to he tested,  
charge put on it said bty was good.
Then 2 people said fuel pump for sure
and that 09 traverse has 2 fuel pumps,
and one could be super pricey. Vehicle
has sat for a year and 4 mos. I
desperately need a reliable vehicle and
this was great for me for a year before
all this happened.  I've heard that fuel
pump could be reasonable If someone
got it from a pull apart place. Another
mechanic said fuel pumps used were
to risky and should spend to just put
new one in it. My only issue before any
of this was that it did burn alot of gas,
but probably cuz pump was going bad.
Which route is best, and least costly:
used pump, new pump, or cut my
losses and find a different vehicle. I
paid 2500 for it initially, and had a great
year enjoying it, and felt it was sound
and had been told I got great deal.
What should I expect to pay to repair?
I was told it felt like it didn't want to
stay on. After returning home within a
day or so it felt like it didn't wanna
keep running and I had to keep giving it
gas to kee A friend had been sitting in
it and playing radio for about 30 mins.
kwouldn't st