Mine cost me in total about £500,backpack,pole,ro unit,brush,hose,sack cart to put it on,to heavy to carry.
It's easy to put the system together,must be cause I've done it.
Backpack is the most expensive bit,I bought mine from usa via ebay,£160.
I have no experience with any other system but I find the backpack to be an excellent bit of kit,hope this helps a bit,
Tim