Regarding finding them on the internet, beware. There are counterfeits out there that have injured people when some of the connections gave way. I bought mine direct from TRX for $300 bucks. About the cost of 5 months membership at the closest gym to me. I had found one on Craigslist for less than half of that but after comparing the pictures in the ad to the pictures on the TRX site, it looked to be bogus.
Like my dad used to say, "Quality is like buying oats. If you want fresh, clean oats, you have to be willing to pay the price. If you can settle for oats that have already been through the horse, that comes a lot cheaper".
I would rather pay for quality any day and know that I have something that will last me for many years.