What I would suggest is putting together a 360 pauper cube, which sleeves, box, and cards, can all be done for under 100 bucks and will keep you guys going for as long as you want.
I'd like to second this suggestion. Cubing is some of the most fun I've ever had playing magic, and as skittensro said it's not terribly expensive. Pauper (just commons) and Peasant (commons + uncommons) cubes aren't too hard to put together, and you have the freedom to build one with whatever restrictions or archetypes you choose. I've seen cube lists that have a tribal focus, cubes that allow drafting of a particular set or block, as well as cubes filled with nothing but "unplayable" cards.
I invested maybe a hundred bucks into the first iteration of my own cube, and probably around another 50 or so since then, but that's a very long-term number. I built the cube over the span of about 4 or 5 months, and while it's still evolving, it is absolutely 100% playable in its current form.
Cube is supreme overlord. Trust in Cube.