ITER isn't a EU but international project and was never meant to be cheap: If you want something to be cheap you don't ask ten different companies in ten different countries to produce one coil each.
Doing it that way was a political decision, it's about technology transfer, building knowledge in different countries, not building a cost-efficient reactor.
You can build more complex stuff much cheaper, e.g. the Wendelstein 7x project costs 1.3bn, and that's including all wages for the general Max Plank outpost in Greifswald for 18 years. The reactor itself did cost 370m. It's way smaller than ITER, yes, but have a look at the Lovecraftian geometry and you see why it's just a tad harder to build.