It's 24x30 right now, it was built over an old an old 20x30 (the opposite direction) pole barn. The barn had a partial concrete floor (20x24) I had to add 6ft to the back and 4 ft to the side, that cost me $875 (4 inches thick). If you look at some of the outside pics, you can still see 3 poles on the left side (facing) of the structure that were from the old barn. I sprang for the high zoot commercial door, $1900, I paid a buddy for the electric on the side $300, plus who knows how much materials, some of which came out of the old barn. According to my checks $7K went into the rest of the building so that's about over 11K, complete, installed. It's 12 ft high at the eves, with 14 ft at the center. The door is 16 wide by 10 ft high.
The reason that I went steel was not only because of the expense but the fact that it could be expanded at a later date.