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

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. Previous Prices: Looking at previous auction prices for coins with similar conditions:
- In 2020, a coin with a condition of 80 was auctioned for 130 euros.
- In 2022, another coin with a condition of 80 was auctioned for 140 euros.
- In 2021, a coin with a condition of 85 was auctioned for 155 euros.

3. Average Auction Price: The average auction price for this coin is 132.25 euros, which can also serve as a reference.

4. Starting Price and Estimates: The current starting price is 110 euros, and the average starting price in previous auctions is 98.29 euros. This suggests that the current starting price is relatively high, which could indicate an expectation of a higher auction result.

5. Auction Trends: The coin has been auctioned 42 times, of which 39 have sold. This indicates good demand and sustained interest in the coin.

Based on these factors, an estimated maximum purchase price could be between 140 and 160 euros, considering that the condition is good and that previous auction prices for similar conditions have reached those levels.

Therefore, a reasonable maximum purchase price could be 150 euros.