It all depends on if you want to do any of the work yourself and how fancy you want to get.
Things are very expensive here and I just had a 42' X 15' pad poured ($3300) after I had the excavation done ($1200) and I built the forms myself.
I did electrical myself ($200/30A) and would do all plumbing myself if it was handy or needed. That would probably be at least another $100~300.
Having elect. and plumbing professionaly done could easily total $2000 to $4500+ depending on the situation.
An aluminum roof with sides will be going in a few weeks from now - that's $6000 (storm rated 100 mph winds & 25# sq/ft snow load). Eliminating the sides would save around $1200.