Recently, thanks to the generosity of Viking Bags, a motorcycle gear manufacturer and vendor, I had the opportunity to check out a bottle holster that they sell.
I was quite impressed with the appearance of the holster, and how easy it was to attach to a bicycle (I did not have a motorcycle to test it on). The materials were of good quality and the stitching was nicely done and strong. It is generic, suitable for adaptation to any dirt bike, and comes with a 1 year warranty. It appears to be big enough to handle most of the can and bottle offerings from stores with ease.
Viking Bags also offers an extensive array of other motorcycle gear, such as backpack bags and saddlebags. Check out their entire product line by clicking here.