To estimate a maximum purchase price for the coin in question, we can analyze several factors:

1. Starting Price: 80 euros.
2. Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape.
3. Auction History:
- It has been auctioned 11 times in the past, of which it has sold 7 times.
- The average hammer price in previous auctions is 57.86 euros, but there is a notable hammer price of 120 euros in a previous auction with a condition of 90.
- The last auction in 2022 had a hammer price of 70 euros with a condition of 85.

4. Price Trends:
- The current starting price is higher than the average starting price of 48.64 euros, suggesting that the seller has expectations of a higher price.
- The condition of 80 is better than most of the conditions of previously auctioned coins, which could justify a higher price.

Given that the coin is in good condition and considering the price history, an estimated maximum purchase price could be positioned between the starting price and the highest recorded hammer price.

Taking all this into account, an estimated maximum purchase price could be approximately 100 euros. This is based on the good condition and potential interest from collectors, as well as the highest hammer price observed in the past.