I DIYed my armorpoxy floor a few year ago. I think the DIY price was about $2/sq ft. I think $3/sq foot pro installed would be a good deal, as long as it's a good product. The painter who applied the "epoxy" on our attached garage when the house was built used a Sherwin Williams consumer grade product. I should've known it was too cheap - it was about $1/sq foot. First it had a bunch of pock marks - looked like air had bubbled up through the surface after the coating had been applied. Then they sent him back to do it again. All he did was scuff the surface and go over it again...so all the flakes from the first application were still visible, but now they'd been painted over. I negotiated a refund for the full price we paid and figured I'll grind it down and redo it someday.
When I started working in a BMW dealer in 2006, we had coated concrete floors, but they were working on an addition to the building. When that was completed, BMW required the dealership to bring the entire shop up to the most recent standards, so the whole shop got red tile floor - think subway tile.
It looks great, but the white grout they spec is a pipe dream...they should just spec gray because it ends up being gray after a month. That tile holds up well as long as it's applied properly with enough thinset behind/underneath each tile. Plenty of GJ members have used tile in their garages and it opens up a lot of possibilities for patterns.
I went against the grain and did armorpoxy white with no flake. It always looks dirty. It shows every scuff. I knew that going into it and accepted it. I'm OK with it. I love the reflectivity of the white. I love not losing a small nut or washer against the flakes. Anything I drop stands out against the white floor.
If you decide to DIY - just make sure you apply it thin enough - I went too thick initially and had to buy more...and don't try to save a few bucks and skip the special spike shoes - you will absolutely need them and use them.
