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

1. Coin Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in relatively good shape. This can positively influence its value.

2. Auction History:
- The average hammer price for similar coins has been 166.69 euros.
- In previous auctions, coins with a similar condition (80) have had hammer prices that varied, but some have reached up to 220 euros (as in the auction on 2019-01-24).

3. Starting Price and Previous Prices:
- The current starting price is 40 euros, which is quite low compared to previous hammer prices.
- The average starting price of 105.95 euros also suggests that the current starting price is below what has been seen in the past.

4. Sales Trends: The coin has been sold in 55 out of the last 60 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros, considering that the condition is good and that the hammer price history for similar coins supports this estimate.

Therefore, a reasonable maximum purchase price could be 250 euros.