To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Starting Price: 125 euros. This is the initial price of the auction.
2. Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally increases its value compared to coins in lower condition.
3. Auction History: The coin has been auctioned once before, with a starting price of 90 euros and a hammer price of 130 euros. This suggests that there is interest in the coin and that it can reach competitive prices.
4. Average Hammer Price: 130 euros, which is the average price at which similar coins have sold in the past.
5. Average Starting Price: 107.5 euros, indicating that the current starting price (125 euros) is slightly higher than average, but not excessively so.

Given that the condition is good and there is a history of successful sales, an estimated maximum purchase price could be slightly higher than the previous hammer price, while also considering the current starting price.

Taking all these factors into account, an estimated maximum purchase price could be between 130 and 150 euros. This is based on the interest shown in the coin and its good condition. Therefore, a reasonable maximum price could be 145 euros.