Precons certainly are good options to get into the game on a tight budget.
Aside from that, playing mono colored decks can help a lot - with the exception of some B and W staples.
In a casual enviroment like yours there are plenty of options if you feel like building the deck yourself. You'll need a well sorted store and/or friends with extensive collections nearby though, because my experience with budgets builds is, that if you have to order the cards online shipping will consume a large chump of your already small budget.
I'd say zada too. Cheap, maybe a little glass cannon, but effective.
Stay with as few color as you can.