wow thanks for all the input! this is a lot to take in at once. I've yet to get a case. is the Ikelite one worth the extra $140?
Let's face it, Ikelite clearly has about the best support of any maker. A plus for Ikelite. But if you really want to save money, the Canon DC35 is a good bargain. The Canon DC35 is much smaller, you can slip it in a BCD pocket.
To me, the main technical advantage of the Ikelite housing is that it has 67mm threads on the lens port. That lets you screw on a 67mm macro lens and some wide angle lenses without having to buy something else to mount them. That's convenient and it saves money. For the Canon DC35, Inon makes an adapter for its 28AD lenses ($100). Dyron makes a 67mm adapter for the DC35, about $75, but it's hard to find. If you buy the deluxe FIX housing, not only do you pay $600 more, but the adapters are another $180, without lens. So having an adapter "built in" is a cost advantage for Ikelite, if you can want those add lenses. For me the Ikelite is easily worth $100 more. I have a lot of 67mm macro, wide and red filter accessories -- so I want that growth path. If you never want to do that, it's obviously not worth much to you.
I trust Ikelite more. Some of the Canon housings leak due to mold release lines at the O-ring, and some say the buttons get sticky over time. That's been reported here and on Amazon reviews, so you would think Canon would address it - nope, not yet! No big deal, I smoothed the mold release lines on mine, no leaks ever. And I work all the buttons in the rinse tank after each dive to flush any salt water for all my housings. With Ikelite, they stand behind everything and would rebuild a sticky housing if needed. Canon just blows you off, fuggedaboudit, buy a new one.
Regarding lens adapters for the Canon DC-35, Inon makes a 28AD version and Dyron makes a 67mm and an AD version. Reef carries the Inon. I found the Dyron at CamerasUnderwater in UK, at about $75 plus shipping. Dyron also have a very compact 20mm wide conversion that fits it, and is much smaller than any other similar conversion lens.
http://www.camerasunderwater.co.uk/general/lenses/index.html
I have not been able to find a US supplier for Dyron but I'm curious enough about it to order from the maker if it comes to that. Dyron has a manufacturer's discussion group on this board, check it out to see what they have. I heard a rumor that Backscatter was considering carrying them, but no reply yet to my query about that.
It is possible to make an adapter for the DC35, similar to ones others have made here. I'd rather buy than make if I can find something reasonable.
Unfortunately the flash on this camera is blocked by every housing, and it's weak anyway. You will probably want an external flash before long. See the discussions here about what your options are.