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

1. Condition: The coin has a condition of 75 (MBC), which indicates that it is in relatively good shape, but not among the best qualities. This can influence the price, as coins in better condition tend to fetch higher prices.

2. Auction history:
- The average hammer price for similar coins is 286.38 euros.
- In the past, coins with a similar condition (75) have reached hammer prices of up to 320 euros (in the auction of 2020-10-21).
- There are also examples of coins with higher conditions (such as 80 or 90) that have achieved significantly higher hammer prices, suggesting that the market is willing to pay more for coins in better condition.

3. Starting price and previous prices:
- The current starting price is 60 euros, which is relatively low compared to the average hammer price.
- In previous auctions, the starting price has varied, but the hammer price has been considerably higher in most cases.

4. Market trends: Since the coin has been auctioned 19 times in the past and has had a sell-through rate of 89.47% (17 out of 19), this indicates a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 250 to 300 euros, considering that the condition is 75 and the average hammer price is 286.38 euros. This allows for some margin for competition in the auction and the interest of other buyers.