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

1. Current Condition: The coin has a condition of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By looking at previous auction prices, we can see that in past auctions, coins with similar conditions have reached hammer prices that vary considerably. For example:
- In 2022, a coin with a condition of 80 was auctioned for 170 euros.
- In 2021, a coin with a condition of 75 was auctioned for an unspecified price but was estimated at 170 euros.
- In 2023, a coin with a condition of 95 was auctioned for 420 euros, indicating that condition has a significant impact on price.

3. Average Hammer Price: The average hammer price for similar coins is 216.82 euros, which can serve as a good reference point.

4. Starting Price and Estimates: The starting price is 100 euros, and the average starting price is 125.77 euros. This suggests that the market is willing to pay more than the starting price on many occasions.

5. Auction Trends: The coin has been auctioned 13 times in the past, with a high sales percentage (12 out of 13). This indicates a consistent interest in the coin.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros, considering that the condition is good and the average hammer price is 216.82 euros.

Therefore, a reasonable maximum purchase price could be 250 euros.