When you purchase a costume, I don't feel that you have the same emotional attachment to the costume that you do when you make it.
For the skirt, check in the patterns for a longer box pleat in the sportswear section of patterns. If you need a specific one to look for, let me know and I can dig through my patternbox for the one I'm using for Haruhi Suzumiya.
For the shirt, you can steal the body of this pattern: Butterick 4684 and the sleeves off of this one: Butterick 5526
A good sailor collar tutorial is the one by Lynleigh which appears to be removed, but has been collected by http://cosplaybrain.wordpress.com/20...llar-tutorial/
If you can sew well, then making a costume such as this will cost you so much less than buying the full costume and you get the added bonus of pride in your creation.
If you have any other questions, let me know!