We use bandanas quite regularly in our shop and make them ourselves. Groomer to Groomer did a great article on how to make them a year or so ago. Basically the way we do it is we buy material that we like at our local Walmart or a place called Joanne Fabrics. Usually we can find something we like on sale so that keeps the cost down.

To make the bandanas cut the fabric into 24" squares. Cut in half this will give you two large bandanas. Cut one of these in half again to make two medium bandanas. Cut one of those in half to make a small bandana. We also save the leftover scraps as we find there are usually some pieces that can be cut to fit puppies. When you can buy material at about $2.00 or less a square yard the cost is not bad.
Scott Facey/FyrLyte

I make bows to coordinate with bandanas. I merely cut a strip of fabric... the size depends on how large you want the bow, but to be safe, cut the fabric a good bit larger than you want the finished product to be. For example, cut a strip about 31/2 inches long, and 11/2 inches thick, to practice. Using a pair of hemostats, I slide a grooming rubber band onto the closed hemostat. Then, lay the fabric across the stat, with the widest part going left to right. The band in lower than the fabric. Lift the upper part of the band up and over the fabric, and slide it onto the tip of the stat. Now the fabric is being held by the band. Holding the stats up, and working on the opposite side of where the fabric is, lift the lower part of the band up, over the upper part of the band, over the tip of the stat. The bow is now nearly done. Leave it on the hemostats, and move the fabric around till it looks attractive and not bunchy. Then, trim the bow to the desired shape and size with your pinking shears. If you want to add decorative trim like a hot glued pom pon or whatever, do so now. I like mine plain. Slide the band off the stats, and either put directly on the dog, or slide the band over a pencil, drinking straw or something so that the band wont slip off. When I get organized enough to make a lot of bows in advance, I cut a lot of drinking straws into 1 inch pieces, and make a tiny notch in them with scissors. I slide the finished bow onto these, and they stay "made." I can then store a lot of them in a box without worrying that they will come undone or get squished. It sure is a lot easier to do than it is to explain. Do try some, they are cute and clients go nuts. There is something entirely too cute about a Yorkie in a red bandana and matching hairbow! I am sure there are many other ways to do this, but this works well for me! Good luck... hope this makes at least a little bit of sense. Daryl