Zoo Warlock has always been a strong archetype in Hearthstone, and that hasn't changed in Rise of Shadows with the success of Magic Carpet Zoo. Unfortunately for budget players, Magic Carpet can be an expensive craft, so this list was designed to stay under a 1500 total dust cost while remaining competitive and true to its Zoo roots. I was winning games on stream with it at Rank 2 with ease, and although I design budget decks for people at the Rank 20 to Rank 5 range, this list could probably be played to Legend in the hands of a skilled player (maybe even me).
As is the goal with most Zoo decks, you should be trying to build an early board advantage via cheap minions, then leveraging that ever-increasing board for lots of value trades while keeping an eye out for face damage with any leftover attacks (or when you're close to securing lethal). This particular list is built around a lot of wide-board synergies, where you'll end up with lots of small minions to buff via Grim Rally or Void Analyst, or to create big threats with Frostwolf Warlord. Really all you need to do is build boards, Life Tap, and reload.
Here's a video of me playing this deck:
You can also watch me play this budget deck and more on Twitch below: