He made interlocking bricks for a raised garden, but I would not want to use aircrete for a structure until it could be approved for a permit. It seems that his shed passed because it had studs, but a design with 2x4s instead of two metal studs would save hundreds of dollars, although that still seems like a fraction of the cost.
The problem is that you cannot just use one 2x4 per panel because you need to attach them. Would they approve two 1x4s nailed together? Wouldn't two 1x4s be thinner than one 2x4? Supposedly a 1" is board is 3/4" thick, but everything 2"+ is half an inch smaller.
Supposedly earth blocks meet code, but I would need to check first. Right now it looks like neither of these are my best option.