some will some won't.

the idea of a drop chip is that it allows the dealer to keep their lower denomination chips in the rack to make change for players and it keeps the drop box from filling up too fast since only one chip is going into the box per hand instead of 3 or 4.

But, some casinos don't want the chips in circulation so they won't sell them. other casinos don't care. it also depends on the denomination of the drop chip you want. if it's a $2 or a $3 drop chip you want, sometimes a poker room will actually use those chips in the games so even though they're drop chips, they're also in general circulation so the house doesn't really care if you buy them or not. other denominations aren't in play so they're more stringent on letting them out.

also, some dealer's could give a crap and if you throw them $3 and ask for a $2 drop chip they'll usually oblige.