speaking for the states of TN, NC, and VA, i can say that as long as you are not changing the plot line of your property, you wont need a permit since the garage is already under roof. however, in theses states, to do any electrical and plumbing, those jobs require licensing and permits those contractors obtain. if you are in the city limits, chances are they will have to be bonded incase they damage city equipment. beyond that, you get an inspection for your permit money. their work is verified for your safety.
here it is $ 25.00 for the first $ 1,000.00 worth of work and $ 5.00 for every thousand thereafter on permits. a neighboring county however, now voted in a flat $ 100.00 on any permit needed. so, it sounds like it varies. i am curious to know the rates in your area.
as far as pricing, i am willing to bet that in California, you can look at anywhere from $ 150-225 a square foot for finish depending on the aesthetics you want to bring in. do some shopping. check to see if what your contractor offers you is less expensive than what you can get the same item for. it will be an investment after all. i like showing my customers where there money is being spent.