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

1. Current Condition: The coin has a condition rating of 85 (MBC+/EBC-), indicating that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin is 84 euros.
- In previous auctions, we have seen hammer prices that varied significantly, ranging from 18 euros to 370 euros, depending on the condition and demand at that time.
- The last auction with a similar condition (85) had a hammer price of 135 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 75 euros, which is reasonable given the hammer price history.
- The average starting price of 43.33 euros suggests that, in general, coins of this reference do not usually go to auction at very high prices.

4. Recent Trends: In the most recent auctions, hammer prices have been in a higher range, which could indicate an increase in demand or interest in this coin.

Based on these factors, an estimated maximum purchase price could be around 150-180 euros, considering that the condition is good and there is a hammer price history that supports this figure. However, it is important to keep in mind that the final price will depend on the competition in the auction and the interest from other buyers.