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

1. Coin Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in relatively good shape.

2. Auction History:
- The average hammer price for coins with a similar condition (80) in the past has been 150 euros (across various auctions).
- In the most recent auction of a coin with a condition of 80, the hammer price was 220 euros.

3. Price Trends:
- The average starting price has been 97.5 euros, but the average hammer price is significantly higher (128.5 euros).
- The coin has been auctioned 24 times, of which it has sold 23 times, indicating good demand.

4. Previous Starting and Hammer Prices:
- In previous auctions, hammer prices have varied but have reached up to 200 euros on some occasions for coins of similar condition.

Based on this data, an estimated maximum purchase price could be in the range of 180 to 220 euros, considering that the highest recent hammer price was 220 euros and that the coin's condition is good.

Therefore, a reasonable estimated maximum purchase price could be 200 euros.