I started testing one of these machines last weekend after getting a rave review from Antoine Roset during his house tour, and I have to say, I am - so far - impressed. This machine makes perfect, delicious espresso for $.50 a cup and is a slim, pleasure to look at.
While you can go cheaper (and more expensive), the Citiz is a great place to start and finish. Full disclosure:
I am extremely conflicted about contributing to the wastestream these coffee pods produce AND the monopoly that Nespresso is creating for themselves, BUT I have to give them credit. It's great coffee, and I LOVE coffee.