Hi ByDesign and hausknwa,
I bought 3 parts for my home (AT&T just couldn't get my phone to work right for 3 years, so I dropped them and got this instead).
Here are the 3 components I needed for my repeater.
The base unit comes with everything you need if you have a strong outdoor signal and just doing one or two rooms (this is the only piece you need for the trailer). These aren't the cheapest prices, the sites are just for reference. (I bought the base unit directly from zBoost, it was the cheapest)
You may not need this if you have a real strong signal outdoors.
Wireless Extenders zBoost Dual Band Outdoor Signal Antenna for YX510-PCS-CEL
You may not need this if you are doing one or two rooms.
Wireless Extenders zBoost Dual Band Directional Indoor Base Unit Antenna Upgrade for Use with zBoost and YX500
The prices just around as to who has the cheapest, I use amazon to find out who has the price of the day.
Good luck guys!