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

1. Coin Condition: The coin has a condition rating of 90 (EBC), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By observing the hammer prices of coins with similar conditions (around 85-95), we can see that the hammer prices have varied. For example:
- In recent auctions, coins with a condition of 85 have sold for around 110-150 euros.
- Coins with a condition of 90 have reached hammer prices of up to 280 euros.

3. Average Hammer Price: The average hammer price for this coin in the past has been 98.74 euros, which is also an important indicator.

4. Starting Price and Estimates: The starting price is 50 euros, and the average starting price is 65.9 euros. This suggests that interest in the coin may be moderate, but given its condition, the hammer price is likely to be significantly higher.

5. Auction Trends: Since there are 3 auctions scheduled in the coming days, this may increase competition and, therefore, the hammer price.

Based on these factors, an estimated maximum purchase price for this coin could be between 150 and 250 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. A price of 200 euros could be a reasonable target, given the current market context and the coin's condition.