To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 75 (MBC), indicating that it is in an acceptable state, but not of the highest quality.

2. Previous Auction Prices: By observing the auction prices of coins with similar conditions (75 and 80), we can see that:
- In several auctions, coins with a condition of 75 have reached hammer prices ranging from 60 to 90 euros.
- Coins with a condition of 80 have achieved higher hammer prices, in the range of 90 to 140 euros.

3. Average Hammer Price: The average hammer price for this coin is 73.66 euros, which also provides us with a reference.

4. Starting Price: The starting price is 200 euros, which is significantly higher than the previous hammer prices for similar conditions.

Given that the condition of the coin is 75 and considering the previous hammer prices, an estimated maximum purchase price could be in the range of 80 to 100 euros. This is based on the fact that, although the starting price is high, the actual hammer price for similar conditions has been lower.

Therefore, a reasonable estimated maximum purchase price for this coin could be 100 euros.