How about some nicer casual clothing? Some linen pants, either in the looser drawstring variety, or the slimmer-fitting trouser style (a little more dressy). I also recommend button-front linen shirts.
Agreed. I'd second the recommendation on outlet shops, and also recommend thrift stores and eBay/Bluefly. Or maybe you've got an older relative who you can convince to give you a couple of items? If you're bridging college with job interviews, take advantage of the first time customer deal at Tyrwhitt: at 50% off you can't go wrong. First thing to know, however, is your fabrics. There are forum members better able to discuss this area than I, however I would definitely recommend linen, cotton, and, for the evening, a lightweight wool like 120s. Best of luck.