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

1. Current Condition: The coin has a condition rating of 75 (MBC), which indicates that it is in an acceptable state, but not among the best qualities. This can influence the price, as coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for coins of this reference is 400.83 euros.
- In previous auctions, hammer prices have varied, but there are examples of hammer prices exceeding 500 euros, especially for coins in better condition (such as those rated 85 and 95).
- The last auction of a similar coin with a condition rating of 95 reached a hammer price of 500 euros, indicating that there is a market willing to pay high prices for coins in better condition.

3. Starting Price and Average Starting Price:
- The current starting price is 350 euros, which is slightly higher than the average starting price of 326.33 euros. This may indicate that the seller has expectations of a higher price due to demand or the quality of the coin.

4. Sales Trends: The coin has been sold in 12 out of 15 auctions, suggesting that there is consistent interest in this reference.

Based on these factors, an estimated maximum purchase price could be in the range of 450 to 500 euros. This is because, although the condition is not the best, the price history and demand suggest that buyers are willing to pay a bit more for coins of this reference, especially considering that the average hammer price is around 400 euros.

Therefore, a reasonable maximum purchase price could be approximately 480 euros.