New Yorkers, Im from Jersey and want to apply for a legal istant job at an upscale firm.What do I wear?

I worked at a corporate firm before, but gained weight, gave away all my suits and now I have just casual crappy, overused, business wear. I have been working for a smaller casual firm and sort of let myself go. But now I am at an ideal weight, and now my clothes are to big for me. I dont really have the money for that "Park Avenue" look! What do I do now that I want to make the Park Avenue money?