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

1. Current Condition: The coin has a condition of 80 (MS+). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History: By observing the hammer prices of coins with similar conditions, we can see that:
- In the past, coins with a condition of 80 have reached hammer prices of up to 320 euros (as in the auction on 2018-10-17).
- There are also examples of coins with a condition of 70 that sold for 160 euros (2020-09-17) and 110 euros (2019-05-29).

3. Average Hammer Price: The average hammer price for this coin is 245.02 euros, which gives us a good reference for what buyers are willing to pay.

4. Starting Price and Average Starting Price: The starting price is 110 euros, and the average starting price is 139 euros. This suggests that the starting price is relatively low compared to the average hammer price.

5. Recent Trends: In the most recent auctions, hammer prices have varied, but there are examples of coins with similar conditions that have reached hammer prices of 340 euros (2023-01-31) and 600 euros (2023-03-16).

Based on these factors, an estimated maximum purchase price for the coin with a condition of 80 could be in the range of 300 to 400 euros, considering that the highest hammer price in the past for similar conditions has been 320 euros and that there are recent trends suggesting an increase in prices.

Therefore, a reasonable maximum purchase price could be 350 euros.