Buying an espresso machine is an important decision ? choose a wrong one and you've wasted a few hundred dollars; choose a good one and you will be rewarded for years to come.
Picking the correct machine for your needs is a matter of prioritizing the features that are most important to you. There may not be a machine that is exactly in your budget and has all of the features that you want. For that matter, there may not be a machine for sale at any price that has all of the features you want. You may have to compromise a bit.
The following are some factors to consider:
Price
Price is definitely a consideration for most people. As a general rule, you do get more for the extra money - more metal, less plastic, higher-quality workmanship, better support, more controls. On the other hand, if you just want an occasional cappuccino, or if you rather buy other things with your money, most cheap machines can make a pretty decent drink.
Espresso machines are definitely not cheap, but, compared to going to Starbuck's every day, it may not take long at all for a good machine to pay for itself. Spending $3 every weekday at the local coffee house translates to $750 over the course of a year. You could buy a great machine for that amount that will last for years to come.
Type
Moka or Steam - Steam provides pressure to push water through a bed of coffee grounds. No real controls on pressure or temperature. Length of brewing time is controlled by operator.
Semi-Automatic - Pump provides pressure. Operator grinds, doses and tamps coffee into a portafilter. Brewing pressure and temperature are set and controlled by machine. Length of brewing time (and, therefore, volume) is controlled by operator.
Automatic - Pump provides pressure. Operator grinds, doses and tamps coffee into a portafilter. Brewing pressure and temperature are set and controlled by machine. Machine automatically brews to a predetermined volume.
Super-Automatic - Pump provides pressure. Machine automatically grinds, doses, tamps, brews to a predetermined volume, and ejects the spent puck, all with the push of a button. Some commercial super automatics can also steam milk automatically, depending on your brew selection. Bosch, Saeco and Solis are a few of the brands that offer super-automatics.
Lever - Lever pushes down a piston to provide pressure. Lever pushed down manually by operator. Lever espresso machines are harder to operate, but provide greater control over shot. For those who enjoy the art of making espressos. Lever machines are still offered by the original manufacturer - La Pavoni.
Design
The traditional espresso machine is somewhat square and boxy. If this is OK - great - there's plenty from which to choose. If you would rather have a machine with a more modern design, you might consider the Espressione Cafe Retro, the La Pavoni Cellini or the La Pavoni Pisa. For an old world design, you could consider a La Pavoni Lever Machine.
Boiler
The boiler heats the water for the espresso. Usually, it's made of aluminum, brass, copper or stainless steel. Aluminum heats the fastest, but brass and stainless steel retain heat longer. If you just want one quick cup in the morning, aluminum may work best. If you brew repeated shots, consider brass, copper or stainless. Over the years, aluminum may tend to corrode more then brass, copper and stainless.
Another consideration is boiler size. Smaller boilers (3-5 oz.) heat up faster and are great for 1 or 2 cups, but they generally require more recovery time and may not maintain temperature as consistently as a larger (7-12 oz.) boiler. As a general rule, the more expensive machine, the larger the boiler.
Bar Pressure
The amount of pressure the machine can produce for forcing the steam through the coffee grounds and making the espresso. Technically, only 9 bars are needed, so it doesn't make much difference if the machine produces 15, 16 or 18 bars.
Housing
Espresso machines are made with either ABS shock-resistant plastic or metal housing. If plastic bothers you, make sure you look for a machine with a metal housing. As expected, these cost more, and options in the lower prices ranges are limited.
Size
Remember to consider your counter space and how your espresso machine will fit on it and in your kitchen before buying. Don't buy a machine that's too big and unwieldy.
Pods
Coffee pods contain enough coffee for one shot and are pre-packaged inside of a filter membrane. The advantage of using pods is that they are easy to use ? just open a pod package and put the pod into the pod filter holder. The clean-up is easy since the grounds are inside of the filter membrane, and the grind of the coffee is always correct. Pods are great for convenience and cleanliness.
Disadvantages of using pods are the cost ? they are more expensive than grinding your own coffee, and flexibility ? you can only do single shots with pods. Some machines accept pods; some don't. If you want to have the option of using pods, make sure the machine you are interested in can accept them.
Paul Ballenger has been selling coffee makers and espresso machines for over 5 years. Yes, he loves coffee. He has created an Espresso Machine Comparison Chart which separates many espresso machines according to the factors listed above.