wood shed suggestions

everything is expensive. especially lumber. around here , rural America, there are maybe 6 co. that manu. barn tin. it is crimped from a huge roll of flat. ( $50-60/ square. no rot, last forever. they sell windows for bout $75 each. I would go to Menards or where ever, buy the treated 4 x 4's, some 2 x's, nails, metal screws, and go at it. better building, probably cheaper.
buy their kit, and you will paint it every other year, hail will destroy the roof shingles, .... you won a skill ( circular) saw right? hammer?

but like you said, great for the boy to learn to do something besides electronic game scrap. it will be his small man - man cave!!!