Dog DNA home-test-kit?

We recently adopted a puppy and nobody could tell us what breed he is. They said that the mother was some kind of a mix and nobody knows who the dad is. I've heard about those Home test kits. But I don't know if I would waste my money on that. Do they actually work? Where do I get them?
Or does anybody about how much a "real" dna test at the vet is?
Of course I love my dog no matter what breed he is. I just would like to know because people ask all the time what he is and it makes me feel stupid to say "i don't know". I think as a good dog mommy I should know what breed he is.

What’s your experience with dog DNA breed test?

I know there are at least two: Canine Heritage Breed test (cheek swab) by MetaMorphix, and Wisdom Panel MX (blood sample drawn by vet) by Mars Veterinary. I'm looking for someone who has actually done it and can say whether it's worth it or not. Thanks!

I've got a once in a lifetime dog that has been in my family 15 years. When I take him out for walks, people are drawn to him and constantly ask what breed he is. My guess is Tibetian terrier and medium Schnauzer, but I'd really like to know for sure. Is there a vet or a lab in Chicago where I can take him for DNA testing that anybody knows about?