Mara Storage out by the airport. It's technically a boat storage place, but they have 12 by 25 and I think 12 by 30 foot units with electricity. I have a 12 by 25 and have 2 cars and the remains of my business in there.
Not fancy, and it's not fully paved, but you can't beat the price. The neighborhood looks a little iffy, but I promise it's safe out there. Plus there's a goat.