The price varies quite a bit depending on where you take it, but at an authorized Apple service center it's around 150-200 euros give or take, while at independent repair shops you can get it done for 80-120 euros (sometimes less if they have a deal going). The difference is that Apple uses original parts and gives you a warranty, but it takes longer; local shops are faster and cheaper, though the glass isn't always the same quality. If your phone works fine and you don't mind the glass being aftermarket, honestly the budget option works well, but if you want some kind of warranty it's better to go to the official service.