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 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By looking at previous hammer prices for coins with similar conditions (around 80), we can see that the hammer prices have varied. For example, in past auctions, coins with a condition of 80 have reached hammer prices of up to 90 euros.

3. Starting Price and Average Prices: The current starting price is 45 euros, and the average hammer price in the past has been approximately 44.63 euros. This suggests that the market is willing to pay close to this price, but given that the condition is good, we might expect a higher hammer price.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 80 to 90 euros.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 85-90 euros. This is based on the historical hammer prices for coins of similar condition and the current market trend.