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

1. Current Condition: The coin has a condition rating of 75 (MBC), which indicates that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for this coin in the past has been 242.59 euros.
- In previous auctions, hammer prices have varied, with some reaching up to 900 euros in higher condition grades (like 90).
- Most hammer prices for coins with similar condition (75) have been in the range of 130 to 320 euros.

3. Starting Price: The current starting price is 300 euros, which is slightly higher than the average hammer price.

4. Sales Trends: The coin has been sold in 44 out of 46 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 400 euros, considering that the starting price is 300 euros and that higher hammer prices have been reached in previous auctions for coins in similar conditions.

Therefore, a reasonable maximum purchase price could be approximately 350 euros.