That's actually only cheap because of the free shipping - in Germany 450W panels are at about 55-60€ retail right now, for example. So a balcony set (2 panels for 1kW total, plus inverter) is about 150-200€, depending on the specific parts. Both exluding shipping, though.

Prices fell dramatically in the last few years, if I understood things correctly the high prices in the US are mostly due to tariffs.

That’s right. The current US president just reversed some of the previous administration’s Infrastructure Act which provided about 30% tax credit for installing solar.