>>57998563
Late but ETB = Elite Trainer Boxes.
Admittedly kinda hard to come by at sane prices right now because of scalpers but they're equivalent to mtg fat packs
Most people only care for the boosters in them so they'll offload the energy packs/dice/etc in them for like a buck or less. Just pulled this picture off ebay but yeah thei've got a decent chunk of each type in them