If you really want to experience the best possible coffee buy the best possible coffee unroasted and roast it at home. A $20 popcorn air popper makes a decent entry level roaster and really good beans can be found at Sweet Marias, among other places. Good, thorough instructions on how to roast your own beans are there. A good starter bean would be their Java, Sumatra or Sulawesi. These are low acid beans that work well at a wide range of roast levels. Brazils are another possibility. Brazilian beans are a primary ingredient in Illy espresso blends.

Personally, I tend to drink a lot of East African beans roasted fairly light and brewed in a presspot. But a do have a decent espresso machine (Gaggia Classic) and a Zassenhaus hand cranked burr grinder.