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 fairly good shape, but not the best possible condition.

2. Previous Auction Prices:
- In previous auctions, the hammer prices have varied, but we can observe that in similar conditions (around 70-80), the hammer prices have been in the range of 100 to 240 euros.
- For example, in the 2021 auction, a coin with a condition of 70 was sold for 240 euros, and in 2022, another with a condition of 70 was sold for 200 euros.

3. Average Hammer Price: The average hammer price for this coin is 163.85 euros, which is also a good indicator of the market value.

4. Starting Price: The starting price is 170 euros, suggesting that the seller has expectations of a reasonable hammer price.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 200 to 250 euros, given that the condition is good and previous hammer prices for similar conditions have reached those levels.

Therefore, an estimated maximum purchase price could be approximately 240 euros.