I've never interviewed in a suit, and I've been offered every job I've managed to get to the interview stage for. The most I've worn is formal shirt, slacks, nice shoes, and a tie, and that was once for a temp agency (and it was probably too much), another time for an event production company (it was DEFINITELY way too much), and a video game QA company (I could have worn less but it didn't seem to matter).

The event production company was pretty close to being a startup, and it was clear from the moment the door opened and I saw the place and the employees that I was overdressed.

I don't remember what I wore to interview for the video game company I worked for a few years ago, but I'm pretty sure it wasn't too fancy. If I was interviewing for a startup with less than twenty employees, I'd be pretty comfortable showing up in jeans and a collared shirt of some sort.