The bag I just got was 17$ Cheap but it will hold food, any good top entry duffel bag should work, you will need more than a backpack, I also have a maxpedition full of extra AR mags. I think a good .22 maybe a 10/22 would be great, ight weight ammo, easy to silence and cheap! I am also going to stuff my XD 9mm in there with 200 rounds.
The sub 40 is also compact and its a .40 with peep sights!