To estimate a maximum purchase price for the coin in question, we will consider several factors:

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

2. Previous Auction Prices:
- The average hammer price for this coin has been 231.8 euros.
- In previous auctions, hammer prices for coins with a similar condition (75) have varied, but there are examples of hammer prices exceeding 200 euros.

3. Starting Price: The starting price is 100 euros, which may attract more bidders, but does not necessarily indicate the final hammer price.

4. Market Trends: Since the coin has been auctioned 525 times and has had a high sales percentage (471), this suggests there is consistent interest in this coin.

5. Comparison with Previous Prices: In past auctions, coins with a condition of 75 have reached hammer prices ranging from 95 to 320 euros, depending on demand and other factors.

Based on these points, an estimated maximum purchase price for this coin could be in the range of 250 to 300 euros. This is based on the average hammer price and the price trend for coins of similar condition.