Card sleeves for the Warehouses? That seems a little extreme because you aren't shuffling them. But if you are worried about damage from spills, you could probably just try to shrink wrap them or get them laminated. Or for a super cheap approach, just go with sandwich bags or possibly snack-size plastic bags. They won't fit perfectly, but they should get the job done.Even if you had to shuffle them, the fact that they're face up and not hidden at any course of the game would be my reason to forgo sleeves for these.
Sandwich bags are probably the cheapest option.