I have a Ranco ETC single-stage and really like it. It can be set for heating or cooling and allows setting the differential (dead-band) as well. I had a Johnson & it fried itself. Don't know about a site, I purchased mine at a LHBS
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk