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

1. Current condition: The coin has a condition of 75 (MBC), indicating that it is in quite good shape.

2. Auction history:
- It has been auctioned 7 times in the past, of which 6 have been sold.
- The average starting price has been 20.71 euros and the average hammer price has been 31.17 euros.
- Previous hammer prices varied, but the highest recorded is 50 euros.

3. Previous hammer prices:
- In 2015, it sold for 50 euros (condition not specified).
- In 2016, it sold for 35 euros (condition not specified).
- In 2018, it was estimated at 35 euros, but it did not sell.
- In 2019, it sold for 34 euros (condition not specified).
- In 2022, it sold for 12 euros (condition 70).
- In 2024, it sold for 16 euros (condition 70).

Given that the current condition is 75, which is better than the conditions of the coins that sold for 12 and 16 euros, and considering that the highest hammer price was 50 euros, we can estimate a maximum purchase price.

Estimated maximum purchase price:
- Based on the average hammer price (31.17 euros) and the highest recorded price (50 euros), a reasonable maximum price could be between these values.
- Since the condition is better than some of the coins that sold for less, a maximum purchase price could be around 40-45 euros.

Therefore, an estimated maximum purchase price for this coin could be approximately 45 euros.