I haven't bought one in a while, but I think they're somewhere in the $16 range.
That being said, the coffee available to fill them with is Nescafe - not real, brewed coffee but rather syrup added to hot water to produce a coffee-flavored beverage.
I know I may be mixed up, since we've stayed in literally every single resort on property, but I remember many of them having little, "motel" style coffee makers in the rooms already; just can't say for certain if ASMu is one of them. I don't think they are specifically prohibited, in the way that curling irons and such are not prohibited - open flame is a no-no but I think a small coffee maker would be fine. The question is, do you need to bring one, or is one already going to be there (so all you'd need would be the coffee)?