Prices are on the first post on this topic. Premium account have way more advantages. some are: Super shop wizard, webmail, Webmail SSH's, Scratchcards, AND LOADS LOADS MORE.
You also have a much higher chance of getting REs..also, im pondering getting a year for one of my acounts, ive got 3mil to spend, but im hesitant...maybe after a few good restocks =D
Premium costs about US$8 a month, About $100 a year per account. There are way lower chances of being frozen on premium. I have been on this site for a month now using an ABer and NEVER been frozen.