In Germany, competition seems to work in this case, so it is free. I believe SEPA dictates that an intercommunity transfer may not be more expensive than a transfer within the same country. So if a bank in country X charges you 4€ to receive money from another bank in the same country X, it may also charge you 4€ for receiving money from Germany.
I've been paying like 0.9eur fixed fee. However often they are free. I don't know what exactly the logic is with the fees. Anyway I wouldn't see it as a suitable method for small retail payments.
Interestingly, Erste have it off by default in the mobile app so I always have to turn it on for each transfer.
Non-free transfers between those banks can take about 1 hour but if too late in the day then 1 business day.