I think drystacking would work very well for DIY type projects, as those tend to be smaller than the 4000+ sqft mansions a lot of people seem to be fixated on today. If you build something in the 500-2000 sq ft range, the cost of concrete of easier to deal with. Also, drystacking allows you to mix and pour all the concrete yourself, and just build as you have the time and money. A course of block here, two courses there, and before long you have your walls up.
I would plan to go overboard on waterproofing for a dry-stacked building, though. I don't know just how effective the surface mortar is as a waterproofing agent, but I do know that before it's applied a drystacked wall will leak like a sieve. In fact, you can see cracks of light through many/most of the joints between blocks.

If I were doing such a building, I'd definitely plan to use surface mortar, and then another sealant - possibly something like roofing tar. And (if it was bermed) a french drain at the foundation level and another just below the surface (to catch and direct runoff).
Edit: Just as an example, a 10x20x8 dry stacked building (without accounting for a door or windows) would require roughly 500 8x8x16 blocks, 3.5 - 4.5 yards of concrete in the foundation (assuming a 4" slab with 12"x12" footings all around), and another 4.5 yards or so to fill the cores of all the blocks. That comes to a total of about 300-325, 80lb bags of concrete. At $3.40 each, that's a bit over $1100 for concrete. Assuming the blocks are $1.25 each, you're looking at about $1800 in block and concrete.
In addition to that, you'd have to factor in cost for rebar in the footings and walls, insulation, surface mortar, water sealant, roof materials, and any interior finishing you have in mind.