DIY Spindles
It's very cheap and easy to make your own spindles, either for personal use or for use in the classroom, at demonstrations, workshops, etc. The ones that I made for my workshop and that I have been spinning with myself are made from dowels, wooden toy wheels, and cup hooks all bought online in bulk. A few words of caution: the dowels I bought ended up being quite hard wood. I had to drill into them with an electric drill to get the cup hooks in, and even that was quite difficult when it came to keeping them centered and not splitting the shaft. The toy wheels I bought are quite small and light. This makes these spindles very difficult for beginners to use, because when you set them spinning they only spin a super short amount of time. Also, if the size of your dowel and the size of your hole in your whorl are the same, it will be a tight squeeze trying to get them to fit together (which you do want). Some of them I couldn't get on the shaft at all.
Another common starter DIY spindle is made with a dowel/chopstick shaft, a CD, and some sort of rubber grommet to help the CD hole fit the shaft. The wide diameter of the CD means that the spindle will spin for longer.
Another bonus tip is that you can use a pencil sharpener on the end of a dowel to give it a tip at the end which can enable the spindle to be used supported.