Where can I find garage building plans?
In order of increasing cost:

This website has a few good plans for simple garages available at no cost.

TodaysPlans looks like it has some good plans for free, but you have to get them through email.

Mybackyardplans has a few for free, but they look to be low quality.

This website has them starting around $70.

JustGaragePlans has a wide range to pick from, but they're going to run $100+ per plan.