So, to tally things up:
12x20 portable garage: $349 (with MI 6% tax and 25% coupon)
Some treated 2x6s: $38 (half new, half were old scraps on hand)
~55 6x8x16 concrete blocks: $90 (had a few on hand already)
Part of a pile of gravel: $140 (I got kinda ripped off on this gravel load)
Not counting spare/re-used screws, chunks of wood, old rebar, etc. I love scrounging together a project with minimal purchases.
Grand total: $627 Dangit! Over-budget! haha, I had not actually totaled anything up until right now.
In any case, this is 12x20 of covered storage (ok more like 11x20' on the inside) for $630, as compared to the 20x21x9' metal carport next to it that was a whopping $3400. BUT, the carport was the price fully installed, and assembled in just 2 hours by the fastest working mexican crew I've ever watched. I'm glad to have both structures.