If you think an espresso machine is going to be the machine for you, there are a few things that you should consider before your purchase.

Number one is knowing how an espresso machine works, because they can be personalised to suit just how you like your cup of coffee.  Manual machines are a little more fiddly as adjusting the pump pressure even slightly can dramatically affect the taste of your drink.  The more automatic a machine is, the easier it is to operate and the less you have to do as the user.  So, first you need to decide on a manual, semi-automatic or an automatic machine.

Next comes which model to choose and this will be dependent on what you need from your espresso machine.  To some extent you will get what you pay for.  A cheap machine is likely to be a steam-driven variety which produces much less pressure that a true espresso machine so watch out for this.  You can expect to pay in the thousands for a super-automatic model and high-usage Commercial machines will fall into this category. 

As for brands, there are no hard and fast rules for brands to stick with.  Go with your experience of brands that have been reliable in the past, check guarantees and look into what product support is available once your machine is at home.  Most importantly, your espresso machine has to meet your needs so do your research and pick a machine which will serve as an investment for years to come.