Based on the feedback I received after I increased the price of the premium plan a few weeks ago, it became clear that that was the wrong thing to do (while Mark likes to believe he's perfect, the evidence surprisingly suggests that's not always the case). So I have rolled back the premium plan price to what it was before, $10/month. Groups that signed up at $30/month have been credited with two free months.
In addition, I have added a yearly billing option, for $99/year. If you are currently on the monthly plan and wish to change to yearly billing (or vice versa), it's easy to do; just go to the Billing tab under the Admin menu and there will be a button to switch.
Please let me know if you have any questions.