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

1. Current Condition: The coin has a condition rating of 75 (MBC), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price in previous auctions is 43 euros.
- The coin has been auctioned 19 times, of which it has sold 14 times, indicating good demand.
- Previous hammer prices for coins with similar conditions (75) have varied, but there are examples of auctions reaching up to 80 euros.

3. Starting Price and Estimated Price:
- The current starting price is 40 euros, which is a good starting point.
- The estimated hammer price in previous auctions has been up to 100 euros, although this may be an extreme value.

4. Price Trends:
- Looking at previous hammer prices, it seems that coins with a condition of 75 have reached hammer prices between 60 and 80 euros in the past.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 70 to 80 euros. This is based on the historical hammer prices for coins of similar condition and the demand observed in previous auctions.