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

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

2. Current Starting Price and Previous Prices: The current starting price is 1800 euros. In previous auctions, hammer prices for coins with similar conditions (around 90-95) have varied, but some have reached hammer prices of up to 1100 euros (as in the auction on 2018-03-08).

3. Price Trends: The average hammer price in previous auctions is 316.42 euros, but this includes coins of various conditions. Given that the current coin's condition is high, it is reasonable to expect that the hammer price will be significantly higher.

4. Comparison with Previous Hammer Prices: By observing the hammer prices of coins with similar conditions, we can see that they have reached prices of up to 1100 euros. However, since the current coin's condition is 95, it is possible that the hammer price could be higher.

5. Final Estimate: Taking all these factors into account, an estimated maximum purchase price could be between 1200 and 1500 euros, considering that the coin is in very good condition and that interest in high-condition coins may lead to an increase in the hammer price.

Therefore, an estimated maximum purchase price for this coin could be 1500 euros.