Anyone lay their own concrete?

I am building a garage right now , I would probably have had it built but could'nt even get contractors to return my calls so this is the way I went , I built these about 40 years ago so I knew what it would take , get the site ready , dig your holes for the posts , buy the posts , 2x4's for the roof and perlins , buy the steel for the roof and find someone to put it under roof for you mine is 24x40 and amish that put mine under roof had it up and done in 7 hours and 50 minutes cost me 2500 , they aren't any cheaper but they are fast but I am in central pa you can do the perlins and siding yourself I put 2x6's leveled around the outside of the base and am putting stone on top right now so that when done It will 5 inches to the top of boards the concrete is going to cost 3700 poured and finished , not a job to do yourself if it goes bad the only way to fix it is a jackhammer and alot of un-mentionable words.