In reply to critter:
I'm not sure that's true anymore since the opening of all the Alpkit stores. A lot of their products are now similar in price to Rab, ME etc. Certainly, the days of mega cheap dry bags, titanium oddments and cheap bits of camping esoterica are long gone.
To answer the OP, it'll be due to non-branded generic materials rather than cordura or the like. I don't have direct experience of the Orion beyond having a play in the shop but I have the Presta which I use as an everyday cycling bag as well as a day sack and have been really impressed with the quality and longevity. The zips are YKK and the build quality is solid. Mine is a few years old and is still in great nick.
If the Orion has the same material then I suspect it isn't going to be the sturdiest being dragged over abrasive rock but I'd certainly consider visiting an Alpkit shop and having a look at it.