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

1. Coin Condition: The coin has a condition rating of 80 (MBC+), which indicates that it is in fairly good shape, but not among the highest qualities (FDC).

2. Auction History:
- The average hammer price for this coin in the past has been 65.76 euros.
- Coins with the same condition (80) have been auctioned with hammer prices that varied, but generally, the hammer prices for coins of similar condition have ranged from 20 to 90 euros, depending on demand and other factors.

3. Recent Trends:
- In the most recent auctions, hammer prices have shown a trend of being in the range of 50 to 90 euros for coins of similar condition.

4. Estimated Price: The estimated price for this coin at auction is 65 euros, which is also a good indicator of the expected value.

Based on these factors, an estimated maximum purchase price for this coin could be around 90 euros, considering that this price reflects both the condition and the auction history as well as the current market trend. However, it is important to be aware of the competition in the auction, as this can influence the final price.