The most cost effective by far is a Greenstar juicer.
There are three levels of juicers. Centrifuge (cheapest and lest effective); Auger Twin Gear (some are better than others...The Greenstar is the best in this category because it operates at a slow speed to offset heating up the juice): Juice Press such as the Norwalk (minimal gains over the Greenstar and very costly). Twin gear auger type of juicers wern't around when Norman Wlaker commisdioned the Press type. In its day it was the king.
A Greenstar also does wheatgrass.