I would buy as much bike as you can and wait on accessories (well at least ones like aerobars). We spent $600 on my first bike, before the year was up I wanted a better bike. I had to wait another year and a half to get it.
You can't wait on shorts and such, but you could try to bargain shop those. Investing in a great bike will make you happier in the long run.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan