Paul, this is exactly what I was thinking. $2-$2.50 sq/ft is what I can afford. I know what I'm capable of and I know I can do just as good a job or better then someone else. The only thing I loose is the time. But for $3-$4 sq/ft difference in price I can live with that.
That's exactly how I felt about the project. Also, some do choose tile, which can be about the same cost as epoxy, depending on choices. Well, not sure how big your floor is. For a 1 car garage space, you can buy a 4.5" angle grinder, at least 8.5 amps (black and decker makes a good one cheap) with a diamond grinder wheel (dewalt from amazon makes a good one for about $42) and you can grind for about 12 hours or so, plus or minus depending on how hard your cement is. If you have a 2 or more car garage amount of space, step up to the 7" angle grinder and the 7" dewalt double row diamond wheel to do it much faster. If you have more than that or want to save time, you can rent from places a more professional floor grinder where you get to stand up to use it. Some also recommend the diamabrush attachements for a hand grinder or a pro floor grinder. I didn't use those because they are more expensive than the dewalt wheels, which work great.
Do get a good 100% solids basecoat epoxy. You don't have to put a top coat on that if you don't want to. If you don't do flakes, you can just leave it alone. If you do flakes, that adds cost. And then you really need to do a clear topcoat over the flakes to protect the flakes which adds alot more cost. I did clear epoxy but mine was in a basement. Generally, use clear in a polyurethane for uv protection and also a harder top layer for scuff resistance too than clear epoxy can do. But it is very thin, so you may want two coats of poly on top as a clear. You will need spike shoes. I made my own easily. If you go the hand grinder route, you must have a couple things. You need a shop vac with drywall dust bag for fine dust. You must use a resperator mask while grinding to be safe with dust. You also need a special vac connection to your hand grinder. I made my own for that too from a metal cookie tin that worked great and took an hour to make. Doing my own shoes and dust connection for grinder saved me $50 on the project. Buying my own wheel and grinder vs. renting a few days saved me at least $300, maybe more because I had to do mine in two steps and also spread out in time, not all at once, so would have needed multiple rentals. Doing the epoxy job myself also saved me at least another $3-400. Primer coat is a great idea unless you want to save money, because epoxy needs epoxy as the primer. You can't use any kind of paint type primer - won't work. OR, you could just do your basecoat and if you have problems, then that could be your primer coat and you could buy more for another basecoat on top of it only if needed. Primers can reveal air bubble issues or fisheye issues from contamination and also fill in rough areas a bit before another topcoat, which then looks smoother. At the least, you do need to fill in cracks/holes/rough areas with some epoxy first before your main coat. I just did that with cheap $22 rustoleum 100% solids patch kit where needed and it was fine. Mix 4:1 with white silica sand to epoxy to stretch out the pricey epoxy as much as you can for the cracks/holes/rough areas.
Mine turned out good and glad I did it, but as an avid afraid of nothing DIY type, doing it all yourself and learning all needed to be successful with it is more than many can bite off and chew. And I'm a professional mechanical engineer in real life! I love challenges! But this! This is hard! (not counting that 17 year old recently who did a great job and made it look really simple!) I would do it again myself, but now of course, I could do it twice as fast and better too! Those pro contractors if good do deserve what they get because epoxy is not a simple thing to do right. Read the last year of forum posts before you do it to learn from others! Worth spending several weeks of time to read up here! Much knowledge from many posters not often repeated. - Paul