I've only tried the $40 jungle gym and the $180 TRX and the difference is pretty astounding but not everybody wants to spend that kind of money for a portable gym so lots of other trainers have patented their own in the last two years. They range in price from $50, $70, $120. Tell your trainer she should invent the $25 suspension trainer. That would sell like crazy. The money isn't in the equipment anyway. Look at the gliding discs. The money isn't in the disc which are only $15 it's in the workout video membership.
BTW, you can actually
Make Your Own TRX for $26. There's a video and a story on my site about that (bottom of page).
I actually handed my Perform Better catalog over to my dad the other day and said what can you think of that hasn't already been invented? It was a challenge to him because he loves inventing things so I'm waiting for the day when he says hey guess what I invented, LOL.