Change of tires very expensive

Hello guys, I need a new eraser at the back and ordered it online. Now I’m looking for a workshop that changes the tire. In some threads I could find out more often from 12€ or so. That’s far away from my results asked for by phone. Are you building the tire yourself and just letting me do the rebalancing? So without the same rebalancing of the tire (back) it costs me in Berlin between 50 and 100€ WITHOUT REIFEN! Does someone in Berlin know cheap tyre changers / workshops? Greetz, lace