In reply to mangosta:
I used one last year for month long trip to Daxue Shan mountains in central China / Tibet (Minya Gongga mountains). Ordered through my local Nevis Sports shop after similar diffs locating anywhere. Big sack and comfortable (there were only two of us), useful pockets on lid, good expansion lid, strong haul handles (one on back and top front), generally durable; but, belt buckle broke at critical moment (replaced without quibble back in UK and the replacement is stronger); the compression strap under the lid for rope also had weak buckle which meant couldn't really compress; the bits to strap axes to the back were funny elasticated straps rather then more conventional buckles - sounds fussy but were a pain; some of the other straps also unduly fussy and not what you need.
Recall being about £100 which seems reasonable price for a big sack. Have used Berghaus sacks for years - this not as well made as others and doubt will prove as durable. But, suited our purposes, very comfortable carry and held tons of gear.