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 of 75 (MBC), indicating that it is in an acceptable state, but not of the highest quality.

2. Auction History:
- The average hammer price for similar coins in the past is 273.54 euros.
- The condition of the coins auctioned in the past varies, but there are examples of coins with similar conditions (75-85) that have sold for prices ranging between 200 and 300 euros.

3. Previous Hammer Prices:
- In previous auctions, coins with conditions of 75 have had hammer prices ranging from 150 to 280 euros.
- The most recent auction with a similar condition (75) had a hammer price of 190 euros.

4. Price Trends:
- The general trend seems to be that coins with a condition of 75 can reach hammer prices in the range of 200 to 300 euros, depending on demand and other market factors.

Based on these points, an estimated maximum purchase price for the coin in question could be around 280-300 euros, considering that the average hammer price is 273.54 euros and that the condition is acceptable. However, since the coin is not of the best conditions, a more conservative price could be 250-280 euros.

Therefore, a reasonable estimated maximum purchase price would be approximately 280 euros.