I went to a place called "Play it Again Sports". While most of their stuff is used, they sell a ton of new stuff too!
Anyway, I bought a bar for about $15.00 new. It is not the fancy one that is on Beach Body website. Mine...I have a bar and a cap at each end. I had to drill the caps into the door way and the bar fits into the caps...much like a spring rod. You adjust the tension on the pull-up bar so that it is sturdy in the door frame and the caps keep it from sliding down on you. If I need to take the bar down, I just loosen the tension but the caps stay...they have been drilled in!
If you buy something that "installs", it is cheaper...I have the kind of house you can beat up! If you don't want to mess up your wood work or explain to company why you have a metal bar in your door way...I'd get the pricey version like the one at Beach Body.com.
I tried forever to find a deal on the ones like they have on Beachbody.com but had zero luck! If you go my route, check your local sporting goods store.