Considering all the hours I spent looking for ways to do exactly this when I was 12-15... I don't doubt I would've gone through all the trouble and even learned some AWS along the way.
Back in those days the only way I could get a free server was by hosting a phpBB forum on 000webhost and somehow convincing a VPS provider to "sponsor our forum". They'd get a massive banner ad and I'd get a free server to play around with. The good days!
But the difference between a couple bucks a month and $5 once you actually have the ability to pay for stuff online does seems pretty negligible.
In fact, some websites even offer big discounts (like 15%) for payments in boleto since there is basically no service fee.
That is basically how me and all my friends did "online" transactions.
In any case, if it gets kids learning new things under the guise of saving a very limited resource, I'm all for it!
Even after that, I was always frugal and never wanted to spend something like $15 a month for a server for my friends. Now, as an adult software developer, I wouldn't think twice about the fun to dollar ratio of paying for a Minecraft server to connect with some old friends.
000webhost, x10Hosting and SixServe (both had FREE cPanel!!), and never forget those shady reseller control panel hosts like Nazuka.
I'll admit though, the shady reseller hosts were pretty good. Terrible control panel aside, they had very generous CPU/bandwidth/storage limits compared to the free cPanel hosts that had to cut down the costs there.