My first question is how much thought have you put into this project? My guess would be almost none.
So let me get this straight. You are going to invest in a tower and commercial grade antenna. Then you are going to invest in a commercial grade transmitter, commercial grade amplifier, receiver, controller, cavity duplexer and a commercial grade power supply just for starters.
And now you want to put all this equipment in the cheapest type of shelter you can find?
Go to this site and see what is really involved in building a repeater:http://www.repeater-builder.com/rbtip/