Based on the data provided, we can observe that the coin in question has had varying starting and final prices in previous auctions. The current condition of the coin is graded at 85 (ebc-), indicating that it is in fairly good condition.

The average starting price in previous auctions was 85.2 euros, while the average final price was 71.67 euros. The coin has been auctioned 9 times in the past, being sold in 5 instances and not sold in 4 instances.

Considering that the coin will be auctioned soon with a starting price of 75 euros, and taking into account the previous final prices, as well as the current condition of the coin, we could estimate a maximum purchase price around 90-100 euros. This estimation is based on the fact that the average final price has been lower than the average starting price, and the coin's good condition.

It is important to note that the final auction price will depend on the demand at that specific moment, so it is advisable to monitor the auction to adjust the offer accordingly.