Anyone know anything about concrete?

I did the same thing you are thinking about, excavated, formed, rebar, did everything but the pouring. The pad was 22x23 something like that, but too small!! Wish I had made it bigger, but the garage was a used one I bought and had it moved and set down on the pad, so I was restricted. Anyway, for the 22x23 I think I was under a grand having it poured and finished for me. All in $5k movers, concrete but not insulated or wired when I got it. Good luck let...let someone else do it, u dont want 5 tons garbage concrete