If anyone has recently renovated and has white paint left over, sell it to me. I need about 10 litres.

Do not mix cheap paints, you will be heading for disaster. Buy good quality paint and save yourself the headache.

Have you got any recommendations? How about OBI? Or would Kustermann have some good quality paint to sell?

If it's for painting an apartment before you move out, you might want to check what your rental contract says. Some of them specify that a certain type of paint has to be used.

As for where to buy it, I got some pretty cheap from Aldi. I'm not sure if they have it regularly though - it might have been a promotion.

I thought there was a new law saying tenants don't have to paint before moving out...That would save me so much time and energy. As for the paint itself, I'll let whoever whitewashes take care of that.