That's a reasonable price if it includes materials, in my view:
windows are a lot of work if prepped correctly (scraped thoroughly,
reglazed, primed, painted with 2 coats), and I'd insist on 2 final
coats of paint on top of the surface priming. Draw up a contract
where you hold back some $$ at the end to assure your satisfaction
with the final job.
Based on your homepage, it looks like you are in the metro DC area,
which means for that area, the price is reasonable. Why not ask a
professional painter for a ballpark reference?
I didn't feel it was right to do this if
I had no intention of engaging a painter.
As for the caution expressed in another followup
about lending to relatives, I agree on general
principles, but it's the sort of situation
where I never say never.
Proper prep
Quality paint
Experienced Painter
This is the outside of your house, not a closet. This is a job that if
done poorly will decrease the value of your home when it should be
increasing it. If you want to help this guy out give him some jobs
that are not so important. For $2K you should can get a professional
that will provide professional results.