If you want a wider choice of machines, you could use a box which would give you 220V from a 110V outlet.
One way to do this is to use a step-up transformer. (a quick search of google yielded this- http://www.dvdoverseas.com/store/index.html?loadfile=catalog6_0.html)
If you go this route, you'll need to be sure your 110V plug is rated to a high enough current. As you double the voltage (from 110 to 220), you are cutting the current in half (to conserve power). This means if you have a machine that needs a 220V 15A plug, then your 110V plug needs to be rated to 30A (if I am thinking correctly). The best way to think about it is the 110V needs to be able to meet the power rating of the machine (so if your machine is 2400W, then it will draw 2400/220=10.9 A at 220V or 2400/110=21.81 A at 110V; This means that if you are using a step up transformer, you'll need to make sure your 110V plug is rated to at least 21.81 A)
They also make boxes which convert two 110V plugs on separate circuits into one 210V plug (http://www.quick220.com/220_volt.htm). This works by taking each AC wave, putting them in phase (so you get an AC wave, with twice the amplitude). All the stuff about current mentioned above shouldn't apply to this (so if the machine says it needs to be 220V at 20A, then you just need to 110V sockets each rated to 20A).
I've used a step-up transformer before for an espresso machine, but have not used the other boxes (which are cheaper and more elegant)
There are a few manufacturers that have a 110V 2 group machine. There is obvious pros and cons to this. If you are using this machine for a high volume shop you will run into a situation if you have a mid-high volume drink count. The reason for this is that it takes longer to cycle the boiler as it takes longer to heat the water. Also depending on the function of the machine (ex: kiosk or mobile cart) you will need to allow for a large lead time on start up as there is a longer time to get the boiler to temp. If you are using this in an espresso bar then I would recommend a 220V to eliminate this type of problem also you will have a power saving by using 220V as it requires less current and the machine will have to cycle less. Now for the biggest pro to the situation, this type of machine can offer some flexibility in expansion for a business or be used for a good back up machine. The option to use this machine for catering or small kiosks and or off-site functions such as local sporting events or functions is a great way to generate additional income for you. You would not have trouble finding a 110V plug-in at these types of locations the alternative if you have a 220V is to buy a generator for this kind of thing (extra cost incurred) but if you are using this strictly for home use then you would be in a good situation. European based manufacturers mainly make a 110V model for the states based sales..European models will be 240V (308V) machines and since most homes in the U.S. only have 2 220V plugs in a house (dryer and stove) unless you have added this as a retro fit or built your home and asked to have this upgraded. All in all there are few different manufacturers to choose from if this is the kind of machine that you desire or if you way the pros and cons of this and you are going to use this for a true commercial use then you might want to consider a 220V machine.
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