I like the mans thinking (euro1603). Its pretty simple, air gets sucked in, so who really needs a $400 piece of pipe which probably costs $40 to produce? Unless it was gold plated then I might consider.

Go the ebay special. Even if it doesnt fit, you can make it fit. failing that, meh, it was only $50 or so dollars - it'll make a nice addition to your rainwater catchment system on your house.