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+). This is an important factor, as coins in better condition tend to reach higher prices.

2. Starting Price and Average Hammer Price: The starting price is 150 euros, and the average hammer price in previous auctions is 146.93 euros. This suggests that the hammer price is usually close to the starting price.

3. Sales History: The coin has been auctioned 111 times, of which it has sold 106 times. This indicates good demand and a history of successful sales.

4. Previous Prices: Looking at previous hammer prices for coins with similar conditions (80-85), we can see that they have reached hammer prices that varied, but some have reached 240 euros (as in the auction on 2018-10-17).

5. Recent Trends: In the most recent auctions, hammer prices have been in a range of 150 to 220 euros for coins of similar condition.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros, considering that the coin is in good condition and has a history of successful sales. This also takes into account the possibility that buyers may be willing to pay a little more for a coin in good condition.

Therefore, an estimated maximum purchase price could be approximately 220 euros.