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
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.
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.