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

1. Condition of the coin: The coin has a condition rating of 95 (EBC+), indicating that it is in very good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction history:
- The average hammer price for similar coins is 44.16 euros.
- In previous auctions, we have seen hammer prices that vary significantly, but some examples of coins with similar conditions have reached hammer prices of up to 160 euros (as seen in the auction on December 14, 2020).

3. Starting price and recent hammer prices:
- The current starting price is 18 euros, which is relatively low compared to previous hammer prices.
- The trend of hammer prices for coins of similar condition suggests that the price could be significantly higher.

4. Market trends: Since the coin has been auctioned 199 times and has had a high sales percentage (170 out of 199), this indicates a consistent demand.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 150 to 200 euros. This is based on the historical hammer prices for coins of similar condition and market trends. However, the final price will depend on the competition in the auction and the willingness of other bidders to pay.