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

1. Starting price: 50 euros.
2. Current condition: 70 (MBC-), which is a fairly good condition.
3. Auction history: The coin has been auctioned 3 times, of which it has sold 2 times. This indicates moderate interest in the coin.
4. Previous hammer prices:
- In the auction on July 14, 2022, it sold for 45 euros with a condition of 75.
- In the auction on October 28, 2024, it sold for 40 euros with a condition of 70.

5. Average hammer price: 42.5 euros, suggesting that the selling price usually falls within that range.

Given that the current condition of the coin is 70, similar to the last auction, and considering that the starting price is 50 euros, an estimated maximum purchase price could be in the range of previous hammer prices.

Taking all these factors into account, a reasonable maximum purchase price could be approximately 45-50 euros. This is based on the interest shown in previous auctions and the current condition of the coin.