I would go with a compact. $1,500 is just not practical for a DSLR, i really dont think its too practical for a 4/3 camera either. I would either go with the Canon S100 or new Sony RX100 (more expensive, but has a much larger sensor). Even going this route, if you want a quality aluminum housing, you are looking at $800+ just for the housing (although you could go with a poly carbonate one for $300, i think).
One other option for you, there are some really cheap poly carbonate housing available for the Sony Nex-5n, so I guess you could get the camera and housing for less than $1500
One other option for you, there are some really cheap poly carbonate housing available for the Sony Nex-5n, so I guess you could get the camera and housing for less than $1500