I bought mine from a legitimate Honda dealer on Ebay. This was because they offered the item at the same price as Bernardi or Honda Parts Now, but without shipping costs. Had I bought $75 worth of qualified stuff from Bernardi, Id have gotten free shipping like I did for the one item on Ebay, but I didnt have $75 worth of stuff to buy. Be careful with Ebay and Amazon - lots of third world junk with fake Honda bags and boxes, sold uber-cheap... and a counterfeit lie.
How long? I dont know. I figure an odyssey in mostly in-town use probably sees a decent amount of stress on the AT. I look at it generically like this: Old school of thought was AT service at 36k. Then Dex IIIH got us to 100k (in theory) for light use. These older design ATs generally required a pan drop and filter replacement. So I figure somewhere between 36 and 100k is the right level for non-towing, non-taxi, generally light duty use. Probably a bit on the earlier side for a heavier vehicle with in town use. So I want to do it around 60k, and so Im targeting the next oil change (probably 55k or so?) to do it.
I do drain the AT via the plug, and replace the same amount of fluid, every other change. So its probably pretty clean. But I actually want to cut it apart and see!