What size garage are you doing? 1 car 2 car etc? Or if you know the square footage how much are you looking at.
Do you own or rent?
Reason I'm asking?
You could forgo all the headaches and hassles of cleaning and possible repair to the concrete and just go with a tile system.
Something like
Racedeck or
Swisstrax or
similarThey may be more expensive, but you can take them with you, you don't have to clean the floor and it can cover spawling concrete.
And they look super slick
You can even do solid colors
Once again yes this route is more expensive, keep in mind you can do it in phases too.
Oh and did I mention you don't have the mess of cleaning the concrete.