Not sure which ones you're referring to, so here's a bit of clarification:
SNK manufactured brand "old-style" Neo Geo home cart case - this is the soft plastic case with cardboard backing undeneath vinyl plastic cover that comes with a fragile plastic tray insert for housing home cart games manufactured prior to 1995.
SNK manufactured brand "new-style" or "snaplock" Neo Geo home cart case - this is the hard plastic case with the SNK logo in the mold, and a snap locking clasp, for housing home cart games manufactured starting in 1995 w/Fatal Fury 3
Off-brand video tape storage case originally located and presented by respected Neo member BigBear and dubbed the "Shockbox" - this is the molded soft plastic case that perfectly fits MVS games to create a collectible look on the shelf
The Shockboxes will set you back $7-8 from SouthTown (
www.southtown-homebrew.com) but the official SNK Home Cart cases will be be between $20 for old-style to $40+ for snaplocks.
Sincerely,
Mikhail