If you are on a budget, $12.58 and twenty minutes are all you need to build a fully functional clone of Fitness Anywhere's TRX Suspension Trainer (trxtraining.com).
At $199, the TRX Suspension Trainer is cheaper than most gym equipment. Its body weight resistance exercises are challenging enough for elite athletes yet can be regressed to suit even the most deconditioned individuals (See examples at the TRX, ACE, or BodyLev libraries).
There are lots of TRX clones but this design is uniquely inexpensive, strong, and easy to make and use. I've included simple instructions for an attachment that makes hanging the device a breeze, even for anchor points higher than 9 feet.
1) Two .5" by 4" PVC pipes or sprinkler risers (pre-cut PVC pipe for sprinkler systems) - $0.56 each
2) Two 8' x 1" Lashing straps with cambuckles - sold together for $7.97
3) One 15' or longer x 1" lashing strap - $3.47
5) Tennis Ball (Optional - see last step)
6) Clip / Carabiner (Optional - see last step)
Total Cost: $12.56
Step 1: Prepare long lashing strap
Step 3: Create a handle (2)
NOTE: This is a permanent knot that won’t slip. However, it will reduce the strength of the lashing strap by up to 50 percent! This is why it’s important to choose straps that can hold your weight several times over.
Step 4: Create a handle (3)
NOTE: You can use a lighter to seal the cut edge of the lashing strap and prevent it from unraveling.