I saw these a little while back and had to check them out for the price. It just came in today, and so far I'm happy!
http://www.ebay.com/itm/35L-Waterproof-Hiking-Camping-Climbing-Travel-Rucksack-Backpack-Outdoor-/191154864544?pt=LH_DefaultDomain_0&var=&hash=item2c81b7c1a0 – there are a lot of different sellers with this same item so you may want to shop around.
It came in at 27.3 oz out of the box, and I quickly took it down to 25.3 with a little trimming (removed padded inner laptop pocket and trimmed some straps). There's a flexible plastic and foam framesheet inside that would get rid of a lot more weight, but it wasn't immediately obvious how to get it out without messing with any important seams. I may revisit that.
The only issue I've noted so far is that the torso is very short. Asian sizing, I guess. To solve that, I cut off the load-lifters leaving a little extra webbing, then sewed that directly to the shoulder strap. So now the straps attach at the very top of the bag. It still seems a tad short, but we'll see how it goes.
Some of the hardware seems a little cheap, but overall it seems like it should hold up just fine! Definitely a great deal for anyone on a tight budget!
I can post photos tomorrow if anyone's interested.










