I guess rentals would depend on the dive shop and it probably wouldn't hurt to call around. Here in Japan I've seen places that say they rent out housings and/or housings + video camera for a few days at a time. Not sure if they are established dive shops or just individuals who are trying to make a few extra yen from their equipment (my guess is the latter).
What probably stops a lot of shops from doing rentals is liability. If you rent a housing and it floods, turning your expensive video camera into a corroded paperweight, who is to blame? Was the housing defective? Or was the user not careful when sealing it up before the dive? It could get messy.
It's really too bad. Being able to rent different housings would be really, really nice. There's so much to choose from: electronic vs. manual controls, available camera controls, external monitor or flip out monitor options, ports, bouyancy and out of the water weight, etc., etc.
If I had to do it over again, I'd probably make a list of all the things I think are important for how I shoot, then start shopping from there. The final decision is so dependent on personal preference.
Good luck.
