You can get an XNA subscription for $99 and start developing for the 360. For the PS3, you need to spend at least $2K and probably sign contracts, etc to verify that you're not someone who wants to hack around.
- The 360 is generally both easier and cheaper to develop for. Niche games obviously need to cut the costs where they can, and you can see this historically from the releases of shmups in previous generations. The branding of the console doesn't really mean anything (i.e PS2 -> PS3). These are companies and will go to what works the best for them.
360 came out first. Microsoft gives incentives for Cave to publish games on the 360. Cave learns the 360 architecture. Cave is now unwilling to learn how to put games on the PS3.
as others have said, it is probably cost prohibitive for devkits, psn licensing, etc. porting takes time and money, so it probably isn't worth their investment to take the gamble, especially since companies like Cave aren't working with a huge safety net of money if things go amiss. It's working for them on the 360, it's working for them in iOS, but it obviously isn't an attractive financial setup to do it on PS3.
I was referring to both the"being on a Sony console" costs as well as the costs of actually porting/developing (time spent coding, etc.). I think you are right that the cost of being on Sony has gone down, but I think it is still cost prohibitive for a small studio to spend the time and money acquiring and working with a devkit, especially when the time and energy of a small staff could be better spent elsewhere.
Again... with all this in mind... It's just good business
