The standard FIRST membership is $4.99 a month, or $19.99 every six months ($3.33/mo).
FIRST Double Gold memberships are $34.99 a month, or $179.99 every six months ($29.95/mo). You're probably thinking, "DAAAMN!" but remember that this gets you $60+ in exclusive merch every month, in addition to the benefits of the standard FIRST membership - and more!
We should point out that FIRST and FIRST Double Gold memberships are separate (i.e., you don't have to have a standard FIRST membership to sign up for Double Gold).
As always, you can sign up for a free Rooster Teeth account to get a customizable profile, participate in community discussions, and set schedule reminders for shows.