You want a machine with the highest pressure you can find. High pressure means more flavour extracted from the espresso.
Forget about machines that foam the milk themselves, the results are nearly always lacklustre. Get some good milk steaming jugs and learn how to do it, the key is in the swirl, foam early and keep the milk spinning, plunging the wand into the milk once the desired amount of foam is created makes the foam condense into a very rich and creamy foam that maintains the flavour of the milk.
In all honesty I don't think you'd be happy with the results from a $100 (I'm assuming US) machine. Ensure you buy only Arabica beans and make sure you set the grinder appropriate to the ambient temperature and humidity, too fine on a humid day means water can condense in the small spaces and soften the bean before it is tamped and pressed when creating the espresso, too coarse on a dry day means the steam goes through the grounds too quickly and the espresso loses it's flavour.
I've been a professional barista both here and in Canada for the last 6 years (the pressure on baristas to perform is much greater here as very few Aussies drink brewed coffee, most of us drink our coffee in cafés similar to the french and italian style, small, generally al fresco and with no affiliation to any large organisation, many of us have identified out preferred types of espresso coffee and many cafés have their own special blends created exclusively for them by the manufacturer so we are fairly knowledgeable about our coffee) and my parents have a Saeco Royal Professional - it was $AUD1800 and so far is one of very few home espresso machines that produces in my opinion, a good cup of coffee.
PS, Starbucks coffee tastes like dirt and is pissweak in it's standard servings.
end rant and advice.
