Add between $75 and $500 to your budget for the cost of outlet installation. Most garages have electricity of some sort, even if it's just a bare bulb in the ceiling and a few outlets spaced around the walls. If you're trying to convert your garage into living space, you'll need a nearby licensed electrician to add more wiring and outlets for additional electrical devices.
If the concrete slab in the garage is the problem, there are more cost-effective solutions than a concrete mason. Most cracking, flaking, stains, pitting or wear can be easily fixed by calling a concrete specialist to apply either an inexpensive epoxy or polyurethane-based coating. These seals are very durable and can make your garage floor look brand new.