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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in relatively good shape, but not of the highest quality (FDC).

2. Auction History:
- The average hammer price for similar coins in the past is 285.67 euros.
- It has been auctioned 10 times in the past, of which 9 have sold, indicating good demand.
- Previous hammer prices varied significantly, with a maximum price of 1600 euros in a 2018 auction for a coin with a condition rating of 95.

3. Starting Price and Average Starting Price:
- The current starting price is 45 euros, which is quite low compared to the average hammer price.
- The average starting price in the past has been 67.27 euros.

4. Price Trends:
- Observing previous hammer prices, there is a trend where coins in better condition (such as those with a condition rating of 95) reach much higher prices. However, since the condition of this coin is 75, it is reasonable to expect that its hammer price will be below the highs reached.

5. Estimation:
- Given that the average hammer price is 285.67 euros and considering the condition of 75, an estimated maximum purchase price could be set in a more conservative range. We could estimate a maximum purchase price around 150-200 euros, taking into account that the condition is not the best and that the starting price is relatively low.

Therefore, an estimated maximum purchase price for this coin could be 150-200 euros.