There are a number of manufacturers of such buildings, but if you're going to erect your own, presumably your search would be limited to manufacturers who sell them in "kit" form. We didn't have the DIY option, and ended up having Morton Buildings do our 24 x 48" garage. We're happy with the result, even though they were not the least expensive choice.

No offence to your husband but he had better check with
the building warranty before he puts brick or stone on the front of the building. He could rust out the steel in less than 5 years if he doesn't know what he is doing. He should know better. your concrete will cost you more than the building. a building that size will need an engineered
drawing and a curb. Once that is done most are in kit form
and you assemble them yourself or you have the opption of
the supplier to do it for you. Nice building. good luck