Don't offer them too cheaply. Typically you want to roughly sell for 4x your buy price. 200 seems good and there should be plenty demand at that price.
Great work. I'll look into this after my vacation as it seems quite interesting for our university courses.
Can I ask your reasoning about not selling them too cheaply? I would like to sell them cheaper then the existing boards since the price prevented me from buying one when I was 13
That's a great motivation. I just want to caution against underestimating some costs (shipping, returns) and leaving yourself a good margin of error. If your goal is to supply as cheaply as possible, you can always lower the price later. Extra profits can always go into improvement :)
And once you start taking money from people you'll have to deliver, it can alter how it feels when working on the project. It can feel a lot less fun, it needs to be worth your time.
Selling them nice and cheap is great if you're going to do one batch as a project and then move on to other things.
If you're still going to be selling them next year and the year after that, you don't want it to become a burden or a chore - it has to feel like it's worth your while to be psychologically sustainable.
What's your goal? Do you primarily want to help other people get gear cheaply or do you primarily want to be rewarded for your work?
Either is fine, but it's important to have a least a few of the latter, a person has got to eat.
Also consider that it will feel like you're doing a good thing at first, but once you have some units get lost in the mail, users try to scam you for free units, etc it will feel a lot more like a job! You will have an obligation that all of a sudden you're not being paid for at all.
That’s good advice. You need to see the costs that are not so obvious including your own time.
You might as well profit a bit in exchange of the extra work and to cover some losses as others mentioned.
Eventually if demand is sustained, you will see clones pop up on AliExpress or the likes of it very cheap anyway. The design is open source after all, and this is plenty of generosity already.
You can consider making a discount if someone ask for it with a university email or something.