You can get one of those 18x21 metal carports and then you can go to Lowes and get more of the same type sheet metal and enclose it yourself and build your own doors if you want some on it.
I bought a "Carolina carport" with sides and gable ends only, and bought matching metal siding at lowes for the rear wall for $1500 less than having it built that way, and installed rollup doors I bought direct from the supplier and installed them myself for almost $5,000 less than having it built with them.
