Pitt,
I've got a cement mixer big enough for two bags. It's great to pour a step or two. I used it to fill 3 sonotubes last year for my tractor shed.
But when it's time to pour a floor, apron, or many feet of walkway, call the concrete truck in. If your job won't meet the minimum, build extra mini jobs to use the excess. Odds are you won't have enough to finish the first form unless you have extra in the truck.
Two years back we poured an apron for my two dog runs. This was to keep the mud out of the house and to ease hosing down the area. Before scheduling the truck, I set a form in front of the woodshed for a nice level slab. It would take big hits from dropping logs, keep the splitter from rolling, and make shoveling the snow way easier.
After pouring the 12' x 20' x 4" apron, the driver told me there was "very little concrete" left.
I asked him to empty the last bit into the form for the shed and I got a "free" 3' x 9' x 4" pad out of it!
Five yards will go a long way to getting a few nice projects done. So roughly $500.00 gets you 337 80# pound bags of of mix! And you didn't have to mix it!
At $3.00 a bag, you saved enough buying mixed to pay for beer and dinner for all your friends that came to float the slab and build the forms.
Oh yeah. Buy the mixer if you do small jobs and masonry all over the place. But think in the $250 range. 3 point or not, my mixer spends most of its time growing bees and getting the air bubble out of my grease gun when I change the cartridge.