I purchased an "Omega" juicer which has been very good. It cost about $400 and has a 15 year warranty. It is heavy duty and made to last.
How often do you plan on using your juicer? That is the biggest consideration. If you plan on using it a lot, you want to get a good quality juicer. If you only plan on using it ocassionally, then you can get by with a cheaper juicer. The best indicator of the quality of the juicer is the warranty. If it is only warranted for 30 days, don't expect much. If it is one year, expect the juicer to last approximately a year with regular use. If you want a good machine that is going to take daily use--long term, look for a 15 to 20 year warranty.
The machines that advertise that you don't need to cut the fruit or vegetables before juicing aren't good choices. It actually wears the motor out trying to force whole items through.