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 an acceptable state, but not among the best qualities.

2. Current Starting Price and Previous Prices: The current starting price is 150 euros, which is significantly lower than the average starting price of 436.97 euros and the average hammer price of 622.91 euros. This suggests that the starting price is attractive compared to auction history.

3. Sales History: The coin has been auctioned 38 times, of which 34 have resulted in sales. This indicates good demand and consistent interest in the coin.

4. Previous Hammer Prices: Looking at previous hammer prices for coins with similar conditions (75-80), we can see that they have reached hammer prices ranging from 240 to 1550 euros, depending on the condition and other factors.

5. Recent Trends: In the most recent auctions, hammer prices for coins with conditions of 75-80 have been in the range of 240 to 650 euros.

Based on these factors, an estimated maximum purchase price for the coin could be in the range of 300 to 500 euros. This is based on historical interest, current condition, and the attractive starting price. A price of 500 euros could be a reasonable limit, considering it is slightly higher than the most recent low hammer price, but still within an accessible range for a collector.