You can find DIY products at most major hardware stores, but I can't remember the brand names.
Still, they are available in the paint department.
The job is easier if you have a already clean and mar-free surface to begin with. Large cracks or heavy oil buildup requires some work. Even with a new garage floor, there is an acid-etching treatment you must do first to prepare the surface for proper adhesion. This is a nasty (and caustic) process...but prep work is the key to good results.
Once that is done, the painting part is easy! The instructions say how long to let the paint dry and cure before you start driving anything over the floor.
You can probably do a 2-car garage for about $80 worth of materials. A typical professional aggregate job goes for around $1500!
