How much profit on DAT dealer purchase price is ok?

Hi, wanted to get me an overview of the potential candidates and on the DAT page once entered the data of the individual vehicles in order to determine the regular dealer purchase price. I found that there were 1-2, which even offer under this price. But the majority demanded from 300,00 € (which I think is completely ok) to 2500,00 € about it. Of course you have to consider whether the car has new TÜV, some parts have been renewed, or maybe it is additional It was also not possible to determine the value of cars that are older than 12 years old. But with the extreme profit surcharges, there would have to be something going on in price terms. It is especially interesting for price negotiations. But to name the dealer directly his current purchase price is perhaps not appropriate either. Unless he is very immovable about negotiations. Now my question is how much profit surcharge is normal or ok. Thank you in advance. Alex