It's €447 one time purchase, or a €224/year subscription.
The one time purchase does not include updates, so if something breaks with next years macOS update I will probably have to pay for an upgrade again.
This license is pretty pricy for something I just buy for fun, but arguably worth it if you use it often. But I am not allowed to use it for any professional purposes at all. If I just wanted to use it to graph the sales numbers of my side projects (probably not the best tool for the job, but why learn another tool if you have one that does the job?), I would need a professional license which is 10x the price.
Being able to run it on the Raspberry Pi for free is nice, but I assume it is also limited to "personal use".
Mathematica is ridiculously expensive. It's expensive because it's professional software, and there are few alternatives. If you use it daily as part of your job, the price is absolutely worth it, but if you don't, it's just way overpriced.
When I left university, I would have loved to keep using Mathematica, but it was just way too expensive to run it on my laptop, for an app that I would just use a few times per year. And logging into a Raspberry Pi just to use an even slower version of an app that isn't known for being particularly responsive in the first place just isn't something that I care about.