We built a 25x25 at our old house...now we did all the labor so it saved a decent amount of money......but if you have an 84 lumber near you they sell garage "kits" other companies offer as well...but comes with architecture approved plans and directions if you need them. they offer various sizes, styles, options, etc. We spec'd ours out, and materials alone were in the $4-5K range, then we had to do the foundation work, it sucked and will never do it again. Had to go 48" down to the frost line and build up from there
. When all said and done i think we had a little over 6-7K in it for completed building and electrical...so only thing left was insulation sheetrock. For under 10K you can have a pretty nice garage.