Hello! Just got my new 5DMkIII gear today, so it's time to let my 550D go. I'm selling the camera (body only) and Nauticam housing (no ports). I've used it for about 3 years; I can't find any information about determining shutter release count, but I'd estimate somewhere around 10,000.
I've never had any problems with the housing or camera, and everything is in good working order. Neither has ever been damaged or flooded. Both have been well maintained, although I've never had any professional service done. I am the original owner.
I shot mostly with a Canon EF 100mm macro and +5/+10 diopters. Some examples are at http://www.flickr.com/photos/blacktoe/, in case you're wondering what kind of shots you can get with this setup.
All spare parts are included (o-rings, etc). I forgot to remove the ball joint in the middle; the balls on the handles are included, but the middle one is not.
Let me know if you're interested or have questions. Thanks!