There is a lot of good basic buyer’s guide type info at:
http://www.happyjuicer.com
http://www.harvestessentials.com/whatjuicisri.html
(also has model comparison chart)
there are different means by which “juicing” occurs and the kinds of things you want to juice will also influence what kind of juicer you should choose. a huge question to ask yourself is “how much effort do i want to spend cleaning this thing after i make juice?” if the juicer you choose is a b*tch to clean, it won’t get used much.