They're most definitely custom. If you're looking for a good base shirt, you can use one of the jersey-knit "athletic/preppy/vintage" fit light blue polos you can find at Target. That's what I used for mine:
Modified it into a button down shirt. The blue material is a sueded synthetic (not sure the right name for it) which seemed to be a good match to the movie. Doing all the work to make it button-down instead of polo probably isn't necessary; you can just stitch the stripe onto the front and add dummy buttons.
The movie track pants were custom made as well I believe. I wasn't able to find any track pants in the right color, so i just went with some slacks I found on clearance at Dillards Fairly close color match, but not 100%.
The shoes are REALLY uncomfortable for long periods of standing... If you want to wear them for anything more than a party every now and then, you might invest in a real pair of adidas.... The payless ones definitely show their cheapness in that department
It was some Tamiya acrylic that I had sitting around from building model kits... But any brand will work, really. Probably best to stick with acrylics (artist's tube or model paint in a little jar)- get a dark blue and a white, and you can mix a bit to the right shade of light blue.