Well, there's always Illy for starters. It is available everywhere, and is generally considered the best of the big time espresso roasters. It's aforementioned reputation leads to its being often overpriced. If you have the right equipment and technique though, you should be satisfied with its results. Another cheaper option I have come to like is Kimbo. Firstly I like the fact that it hails from Napoli rather than Trieste because I find espresso better the further south you go. It's not as well known as Illy, but you can find it easily online by searching "Caffe Kimbo". Recently I have been turned on to a brand called Passalacqua, also from Napoli. The only place I know of in the U.S. to get it is called Caffe Italia Enterprises in Waterbury, CT. You can call them to order, and they have a link to Passalacqua's website on their website. Currently they only stock the "Vesuvius" beans. I was directed to the brand because I was told it is served in a lot of Napoli espresso bars. I have found it to be very good, and would recommend it. It's all I drink now. It goes for $25 for a kilo from Caffe Italia Enterprises, which is a good price.