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 rating of 80 (MBC+), indicating that it is in good condition. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for coins with a similar condition (80) in the past has been approximately 25-30 euros.
- In previous auctions, the hammer price has varied, but it has reached up to 95 euros on one occasion (although that coin may have had a different condition).

3. Starting Price and Average Hammer Price:
- The current starting price is 30 euros, and the average hammer price in the past has been 33.29 euros. This suggests that the hammer price could be in a similar range or slightly higher.

4. Sales Trends: Out of the 22 times it has been auctioned, there have been 18 sales, indicating good demand for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 40 to 50 euros, considering that the condition is good and that interest in the coin appears to be solid. However, since the starting price is 30 euros, it is likely that buyers will be willing to bid more, especially if there is interest in the auction.

Therefore, a reasonable estimated maximum purchase price could be 45 euros.