$12 Total: Pair of classic game cases, with a latch. Condition is pretty good. Holds 40 Intellivision or 20 Colecovision or 20 Atari 2600/7800 cartridges each.
$7.50 Total: Pair (Two) of Nintendo NES game storage cases. I took the inner plastic out that held the games. Allowed me to fit 14 games in sleeves instead of just 10 in each.
FREE: Pair of audio cassette holders, made by LaserLine, flip open. Hold 18 each I think. Each tape case can be ejected with a spring loaded lever. Fits SEGA Master System games.
FREE: 3-drawer case for BETA Max cassettes. Holds 30. It's very big though, and has a bit of a musty odor that I couldn't get rid of.