OK, here are a bunch of pronunciations I found online:
This one makes no sense at all:
[youtube=425,350]http://www.youtube.com/watch?v=82CuWG4K80E[/youtube]
This one's kind of gross:
http://vimeo.com/4154529Here's a Minnesotan going on way too long about it. It's a classic Minnesota pronunciation of the word -- in fact, she has a pretty standard Minnesota accent in general -- but the weird thing is, I don't feel like she defines "uff-da" properly, at least not the way it's used here. She describes it as an expression of strong feelings, positive or negative, like "Yee-hah!!" or "Shit!" But actually, I feel like people here use it in milder circumstances, something like "Wow." "It's supposed to snow six inches on Saturday." "Uff-da!" or "I'm having the entire family for Thanksgiving, so I'll be cooking for 18 people." "Uff-da!"
[youtube=425,350]http://www.youtube.com/watch?v=D8uebax5eX4[/youtube]
And finally, here's the most useful one; you can scroll down a list and hear how to pronounce uff-da in every language. But would, say, an Italian person ever even say uff-da?
http://www.pronouncekiwi.com/Uff-da