No, $20/month has always been their least-expensive plan. In fact, caker (their founder) was adamant for a very long time against creating a less-expensive plan.
(I've been customer for 9 years, and have occasionally hung out in their forums where caker also hangs out.)
You sure about that? I'm almost positive they've had a $10 plan before. When I signed up a few years ago I needed 1GB of RAM and the cheapest plan only had 512MB. I ended up paying $20 (well, $19.95 or whatever it was) and still do. Up until just recently my plan has always been the "one step up" plan from entry level. It was only with the "we doubled everything" announcement that they got rid of the plan below mine.
They've had a $10 plan for a looong time. It's just recently that they got rid of it, and now it's back.