I'm doing the South Beach Diet but I don't have the money or budget to get the food I need for the rest of this month. Until the first week of May I'm going to be doing calorie counting. I may even do it while being on the SBD just to make sure I'm not going overboard with calories.

Any tips or ideas ?

beans!! cheap, nutritious and filling. i think it does fit into south beach also.
tofu- low carb, cheap
cabbage- shred it up and add to a stir fry for cheap and quick veggies

It's tough trying to lose weight on a budget, but it can definitely be done- you just need to be creative and plan meals very very carefully! good luck!