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

1. 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. Previous Prices: By looking at previous auction prices for coins with a similar condition (80), we can see that they have reached auction prices that vary, but are generally above the current starting price of 25 euros. For example, in previous auctions, coins with a condition of 80 have reached hammer prices of 40 to 55 euros.

3. Average Hammer Price: The average hammer price for this coin is 153.86 euros, but this may include coins in better condition. However, it is an indicator that there is an active market and that prices can be high.

4. Auction Trends: The coin has been auctioned 101 times, with an 86% sell-through rate, indicating that there is considerable interest in this coin.

5. Starting Prices and Estimates: The average starting price is 62.11 euros, suggesting that the current starting price of 25 euros is quite low compared to the average.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 50 and 70 euros, as this is a reasonable price considering its condition and market interest. However, if one wishes to be more conservative, a price of 50 euros could be a good limit.