I bought a shed a number of years ago for $1400. It's a 10'x12' aluminum
skinned, 2x4 walls & rafters, t&g pt floors, 2x8 foundation, a couple of
windows, pre-wired, and a 48" door. It's made by Robin's Sheds. Best one
I've looked at. Comes with a 20 year warranty. It's half way there now and
still in excellent shape. Completely waterproof and has survived a
hurricane (cat 1) and several tropical storms here in FL. I'd be hard
pressed to make one for significantly less at the same quality. I figure my
time is worth something too.

The best advice I can give about a shed is calculate what size you want,
then add at least another 50%!!! By the time I get my riding mower,
generator, bikes, and camping equipment in there, that sucker is full. No,
I didn't have all that crap when I bought it... which is why I suggest
buying/building a bigger shed than you currently need. :-)