I came here to say this... Those FRAKTA bags (http://www.ikea.com/us/en/catalog/products/17228340/) are 100% polypropylene (thin strands, even). Polypropylene breaks down under ultraviolet light. The fact that the weave of the cloth is made from fine strands of polypropylene means that it will break down very quickly in the sun.

There's a "fix" though that should be good enough for a camping trip or two! Coat the bag with a powerful sunscreen. I'm not talking about those "SPF 50" spray bottles--those will wear off pretty fast. No, use Butt Paste:

http://www.buttpaste.com/

Yes, it's diaper rash cream but it's 16% zinc oxide which is the primary ingredient in many sunscreen lotions/sprays. Even better, because it's a thick cream it will actually stick to that slippery blue Ikea polypropylene fabric and do a decent job at protecting it from the sun.

How about nylon mesh bags? Nylon is not UV proof but its more UV resistant than the ikea bags. Some sources would be SOME mesh laundry bags and SOME mesh bags used by homebrewers to hold hops and stuff. For those folks who don't like filtering anyway. Or those folks who really do like filtering but don't want hops clogging up the filter, I guess.

Some (most? all?) HDPE is UV stabilized and you can get HDPE garden mesh in large amounts very cheaply. With a lot of sewing work I bet they'd look tolerably good and last a long time.