I realize I'm a little late chiming in.
The simplest way I can think of would be to go to your local climbing/outdoorsy store and buy a single 15-20' length of tubular webbing, which would cost less than $10. For strap adjustment, I found a pair of these
to be sufficient although I haven't exactly been abusing the crap out of them to really test their strength. For handles, just thread the strap through some short PVC pipe pieces. A third piece of PVC can be used as a door anchor. Lifeline also sells their door attachment separately for $3, but the one that comes with Jungle Gym I is basically just a piece of pipe. Not sure what you can do about the foot holds, but you can probably figure something out.
Or you could just buy the basic Jungle Gym. I waited around for Perform Better to sell them on sale for $30 with free shipping.
For $20-30, these things are great because they allow people to do pulling exercises like body rows at home if they don't or can't have pull up bars installed or have a place to hang rings.
One last thing, using tubular climbing webbing won't chafe your arms up like regular straps.