To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape.

2. Previous Auction Prices:
- In previous auctions, coins with a similar condition (80) have had hammer prices that vary, but some examples are:
- 500 euros (2020-10-21)
- 420 euros (2019-11-13)
- 320 euros (2021-06-22)
- 550 euros (2022-10-19)

3. Average Hammer Price: The average hammer price for this coin is 392.45 euros, which is also a good indicator.

4. Auction Trends: The coin has been auctioned 50 times, of which it has sold 46 times, indicating good demand.

5. Starting Price: The starting price is 250 euros, which is reasonable compared to previous hammer prices.

Based on this data, an estimated maximum purchase price could be in the range of 450 to 550 euros, considering that the condition is good and there are precedents for hammer prices in that range.

Therefore, an estimated maximum purchase price could be approximately 500 euros.