I've recently started teaching a bunch of school kids about electronics basics. Get them interested while they're young. Since then I've designed a few simple circuits to show them and looked into getting them professionally made. I thought it would cost loads, but I looked into it and wouldn't you know it...I found JLCPCB.
https://jlcpcb.com/
Their prices are unbelievably good. They offer 10pcs 10x10cm boards for the low low price of just $2. Of course you have to pay for shipping, but that's low too. Basic shipping only costs around 5-10USD, so you basically get 10 boards for less than $10.
Ordering is simple too. You just drag your gerber files onto their order site and everything else is more or less automatic. You just specify what color mask you want, the thickness of the board, some other details...and that's it. In a week or two (depending what kind of shipping you select) you'll have your boards.
I personally ordered mine on thursday nigh and got them on monday the following week.
And the quality...simply breathtaking. Exactly the way I designed the board. No problems, nothing missing, no scratches. The boards even come vacuum sealed and wrapped in bubble-wrap so there's no chance of them getting damaged during shipping.
Bottom line, amazing company, amazing PCBs, amazing prices.