Gaze then, on my beautiful needle rolls:
Needle rolls are the best way I've found to keep knitting needles organized and safe from loss or injury. It has not kept me from buying four sets of size 15 needles, but it does keep your tools at hand. I am also partial to wooden size 15 needles, but I digress.
The larger case holds my straight needles and was bought from the seemingly-inactive Bean's Stock back in April 2006. The smaller, pink case was bought from a stand at the Santa Monica Fiber Fest last year and is made by the local company Boogy Bags, whose website seems to be out of order.
Be not distressed though, equally useful and gorgeous needle rolls are to be had all over the internets, including Etsy.com. Prices average around $20 and range from $5 and up.
Handy with a sewing machine? Make your own damn case; free patterns for sewn and even knitted needle rolls abound. Then you can start your own Etsy store, expand your repertoire to project bags and whatnot, become a famous designer, get all sorts of awards, and eventually settle down into a life of quiet luxury. At least you can avoid buying four sets of size 15 straights.