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 fetch higher prices.

2. Starting Price and Average Hammer Price: The starting price is 75 euros, and the average hammer price in previous auctions is 163.09 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Auction History: By observing the hammer prices of previous auctions for coins with similar conditions (80 and 85), we can see that they have reached hammer prices that vary, but in many cases exceed 100 euros. For example, in recent auctions, they have sold for 190 euros and 240 euros.

4. Recent Trends: In the most recent auctions, hammer prices have shown an increase, which could indicate a rising trend in interest for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros, considering that the coin has a condition rating of 80 and that interest in coins of this reference seems to be increasing.

Therefore, a reasonable maximum purchase price could be 250 euros.