To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current starting price: 75 euros.
2. Coin condition: 70 (MBC-), indicating good condition, but not the best.
3. Auction history:
- In 2016, the coin was auctioned with a starting price of 50 euros and sold for 85 euros.
- In 2022, the starting price was 45 euros, with a final bid of 170 euros, indicating strong interest in that particular auction.
4. Average final bid price: 127.5 euros, which is a good indicator of market value.
5. Average starting price: 56.67 euros, which is lower than the current starting price.

Given that the coin has a history of final bids exceeding the starting price and considering its good condition, an estimated maximum purchase price could be set in a range that reflects both market interest and the coin's condition.

Taking all these factors into account, an estimated maximum purchase price could be around 150 euros. This is based on the average final bid price and the interest shown in previous auctions, as well as the coin's condition.