What do you wear to a job interview?

I have a job interview on Wednesday at an electronics store. Obviously I feel as if I can do said job well, it's just a matter of proving it at the interview. Only problem is that I have no idea what should I wear. I'm looking at my closet now and all I really have is... casual wear. My normal attire consists of coloured jeans, a t-shirt and a flanny / shirt.... but that seems a little too casual for an interview. On the other hand though, wearing something like a suit seems... I don't know. Perhaps overdressed? It's just an electronic store, after all (I don't have experience with interviews. I'm 21 now, but my only interview was a few years ago... and I wore trackpants and a t-shirt because it was McDonald's). I'm thinking about buying [url=http://www.asos.com/au//ASOS/ASOS-Smart-Shirt-in-Long-Sleeve-with-Double-Cuff/Prod/pgeproduct.aspx?iid=2978270]this shirt[/url] and [url=http://www.asos.com/au//Asos/Asos-Slim-Fit-Suit-Trousers-In-Black/Prod/pgeproduct.aspx?iid=2272355]these trousers[/url]. Obviously they're cheap... but I'm broke at the moment because of university and can't afford much more. Would such a thing be suitable, Flood?