Hello juicer; Glad to see more people taking the leap! As far as store bought reactors go---- I am partial to Extreme Biodiesel's product in the $3000-3500 range. On the other end there is an all stainless steel reactor (around $8000) that has a good reputation.
Many people, myself included, built their own systems. Their is a lot of info out there (see apleseed reactor, Girl Mark)
Frank