I get mocked for that frequently, I've got a little wallet for USB sticks that should carry 6 but as they are mostly the thin key shaped ones there's about 15 in there. Most came free from Microsoft or Symantec or some other such company.
At 2 extremes, I have a very old 64mb Dell USB stick that is (physically) huge and has a Windows 98 boot disk on it. Occasionally useful for BIOS/firmware flashes. At the other, a couple of 64gb which aren't actually that useful as for some reason HP kit doesn't like installing Windows from anything larger than an 8gb stick.