$75 for this size automotive grade Exterior Magnetic signs is very reasonable. I make signs for a living here folks. If this was a client project, the cost would be closer to $100 to account for the digitizing and the artwork plotting time. The last set of 2 color magnetic signs I Did for a client were over $100 PER SIGN. (and they were not logos, they were primarily text) These are not inkjet printouts stuck to 8 1/2 x 11 magnetic sheets from OfficeMax. These are commercial grade signs. They are Sealed and UV treated and DESIGNED To be used on a vehicle day in and day out. Other magnetic sheets are not designed for car use.
If you can get your school to do them cheaper for you, feel free. Most schools dont have commercial sign equipment available. And most sign shops will charge an arm and a leg for a one off custom project like this.
I made them available to the GB Community first as there is always someone here looking for something like this. If folks dont want to pay what I'm asking, thats totally Ok with me. I'll sell them elsewhere. Feel free to check with Local sign shops and get a quote from them for Magnetic logos done from artwork you provide. I encourage my clients to shop around and check prices, and they always end up back at my door. I want folks to get the best deal possible. I'm not giving stuff away though. I have time and resources invested in the project. And you get what you pay for.