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 fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for similar coins has been 247.38 euros.
- In previous auctions, coins with similar conditions (70-80) have reached hammer prices that varied, but some examples are:
- 90 euros (condition 70)
- 150 euros (condition 70)
- 240 euros (condition 85)
- 211 euros (condition 80)
- 180 euros (condition 85)

3. Starting Price and Average Starting Price:
- The current starting price is 100 euros, and the average starting price in the past has been 136.22 euros.

4. Price Trends:
- The general trend seems to be that coins with a condition of 75 can reach hammer prices ranging between 150 and 200 euros, based on auction history.

Based on these factors, an estimated maximum purchase price for the coin could be between 180 and 220 euros, considering that the condition is good and that the hammer price history for similar coins supports this estimate.

Therefore, a reasonable maximum purchase price could be 200 euros.