TRX straps are something I have started to use extensively this Summer when designing strength training programs and after about 4 months of use, I believe they are the best product in strength and conditioning. I will stand behind my opinion because of their extreme versatility in the weight room and easy adaptability to any athlete. I really can not describe any other piece of equipment that is easier to use and does more except for maybe a dumbbell set (which is also more expensive).
This product sells for less than $200 I think and what you get for this price is truly amazing. For those that think TRX Straps are a one-trick pony for inverted rows have a look:
All of these exercises can be easily adapted to any athlete size by adjusting the straps and any skill level by adjusting foot positioning. Compared to other pieces of equipment, especially large cumbersome machines (hopefully you are not still using machines at all...) you can not get a better bang for your buck. Give it a try, it will be the best money you've ever spent for your gym or home.