in my opinion mate £120 quid from extend2wash(john hewitt) its a bit pointless making your own,they are well worth the money and last ages,fair play to ya if you can make one as good cheaper (i do it with my poles) but the JH back packs are cheap as chips and well reliable

i wish folk would stop calling me cheap

i've also thought about it myself, the main reason is not cost but i'd want the containers to be interchangeable, having to refill every 20 minutes would do my head. so it would be 25 ltr barrels i worked around size wise, would need little wheels too for when it's full, but would be a lot more compact than a sackbarrow, and carryable if not to full. but not got anywhere with it yet except a crude drawing and cardboard prototype. if i get chance i'll pursue a bit more.
oh, it would'nt have been for the back, more like when carrying a bag
