Based on the provided data, we can see that the coin in question has a grade of 30 (BC+), indicating that it is not in the best condition, but it is not the worst either.

Historically, the coin has had the following starting and estimated prices in previous auctions:

- In 2018, it was auctioned with a starting price of 40 euros and an estimated price of 60 euros.
- In 2017, it was auctioned with a starting price of 75 euros and an estimated price of 125 euros.
- In 2017, it was auctioned with a starting price of 60 euros and an estimated price of 80 euros.
- In 2016, it was auctioned with a starting price of 45 euros and an estimated price of 70 euros.
- In 2022, it was auctioned with a starting price of 30 euros and a grade value of 70.
- In 2023, it was auctioned with a starting price of 50 euros and an estimated price of 90 euros.

The average auction closing price for the coin has been 79.33 euros.

Given that the coin has been auctioned multiple times in the past with estimated prices ranging from 60 to 125 euros, considering the current grade of the coin, the average closing price, and the previous estimated prices, my estimation for a maximum purchase price would be around 100 euros. However, please note that the final price will depend on the demand at the auction and other factors that may influence buyers' decisions.