Need replacement for 2 bose speaker

I have had two calls for replacing or adding speakers in the rear of a vehicle.  In each case the bose system came with a small 2" paper cone/foam surround speaker mounted in the rear of the vehicle... one is a 2007 Mercedes 2XX somthing something 2 seater hardtop convertible which has locations for 4 of these size speakers (left and right for each passenger); the other is a 2007 GMC Yukon which has a 2" speaker in the rear pillar all the way in the back.  Neither vehicle will allow me room to fit anything bigger that these silly little bose speaker. I invision a metal dome mid that's about the same size that can handle some power and play loud.  For some reason both of these clients feel the need for sound comming from behind them and they're willing to do anything to get it. 

The person with the Mercedes I think was offened when I suggested that it's not normal for people to want sound comming from behind them in such a small car with such a fantastic sounding system.  He didn't grasp the concept of front stage.

Anyway, does anyone have any suggestions?  Am I the only one having customers with request such as these?

Cheap...

or expensive