Most painters will charge about $300 to $500 per room for rooms of that size depending on the type of paint you are requesting to be used.  That is assuming that the room is empty and items like crown molding will cost more to paint.

Where is the tile, John? If it is on the floor or anywhere near bathroom moisture, painting is probably not the best solution.

John,

I must confess to never having seen that application. 

I am not sure the finish would look good or even hold up over the long term.  I would also be worried about the potential vapor retarder level interplay with what is behind the tile.