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 rating of 85 (ebc-), indicating that it is in quite good shape. This suggests that its value should be above that of coins in worse conditions.

2. Previous Auction Prices:
- The average hammer price for similar coins is 220.83 euros.
- In previous auctions, hammer prices have varied, but there are examples of hammer prices exceeding 100 euros, even reaching up to 1100 euros in exceptional cases.

3. Starting Price and Average Starting Price:
- The current starting price is 90 euros, which is relatively low compared to the average hammer price.
- The average starting price of 131 euros also suggests that the current starting price could be a good buying opportunity.

4. Sales Trends: The coin has been sold in 75% of the auctions it has participated in, indicating reasonable demand.

5. Previous Estimates: In past auctions, the estimated price has been up to 600 euros in the case of a higher condition (95), suggesting that the value could be considerably higher for coins in better condition.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 150 to 250 euros. This is based on the current condition, the history of hammer prices, and the demand observed in previous auctions. However, since the starting price is 90 euros, it could be a good opportunity to acquire it at a lower price if the chance arises.