This board is for discussing concerns of fishing bamboo fly rods. Examples would be, lines, actions, classic and modern makers actions and the like.
Check local thrift shops, there're usually bags. I use a nice North Face with good articulated straps (probably used by a student for school). Was all of $7. For more room I have a nice Patagonia vest-pack, that is a vest and a pack (hello), and can carry a lot, but I never overpack when fishing. Lunch, water and jacket is it. Good luck.