>>4484371Go look on
china.comCan get smallish 30x20cm camera backpacks with customisable velcro compartment for a fiver and larger 50x 30cm for 20-40$. Larger ones have side straps for tripods and separate compartments for clothes etc and a flat compartment for laptops/notebooks. Also a side flap so you can just pull out your cam, snap a few and put it back easy.
I used a smaller one for a couple of years for shoots but didn't need to carry around tripods and flashes as studios have them in situ. It was great, no damage in that time. I just upgraded to a larger one for about 10$ but it's more flimsy than the small one but it was just to test if the larger one meets my needs better and it's still more than good enough for 6-12 months. Will upgrade again at some point to a more rugged +20-50$ as I don't fully trust it for my larger heavier glass for long walks or location days but I can carry around two bodies, 4-5 lenses, flashes and triggers no problem.
For those prices you can buy and try a couple then buy the legit k&f concept or other brand ones for +50$ if you don't trust them but they're basically the same. Many of them come with waterproof outer covers but the bag itself is sufficient unless you're walking around in a rainstorm for hours. You should wrap items in plastic in the bag anyway until reaching location and practice lens swaps inside the backpack or plastic bags, especially for dusty or desert environments. IMO sand and dust are much bigger risk/issue to glass, especially zooms with moving parts and shutters/sensors than rainwater.