I axed the attic trusses for two reasons. First is i am of the firm belief more storage just created more ****. Second was my code dept said I would have to do full footers and walls if I had them or a second floor of any type. That was another six to ten grand. I like the idea of another space aka man cave or for other family to get away. Not sure it's worth the cost
I believe this may be true for me, or at a minimum I need an engineers stamp on the design. Because I am in Minnesota and our annual temp swings from -20 f in winter to 90+ in summer, I am somewhat resigned to having full footers. Its not absolutely required, but I don't like inviting problems. I'd say your 6 to 10 grand estimate is entirely accurate.
That's interesting - I didn't need stamped drawings for my garage in Minneapolis, although that was 20 years ago and I haven't paid attention to any changes since then. I wasn't required to have full footers either, my 24 x 40 with attic trusses is on a slab and it's been just fine. I rarely see garages in my neighborhood that are built with full footers.
I don't recall the price difference exactly, but while the storage trusses were more expensive it wasn't all that much compared to conventional trusses...I seem to remember it was a matter of a few hundred dollars.
One other thing - my attic space is fine for storage but the floor probably isn't stiff enough to be used for finished living space. However, I'm sure that's just a matter of specifying the right kind of attic truss.