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 looking at previous hammer prices for coins with a similar condition (90 or close), we can see that hammer prices have varied. For example, in past auctions, coins with a condition of 90 have reached hammer prices of up to 130 euros.

3. Average Hammer Price: The average hammer price for this coin is 69.25 euros, providing a solid basis for estimating the maximum price.

4. Average Starting Price: The average starting price is 43.63 euros, indicating that starting prices are usually lower than hammer prices.

5. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have shown an increase, suggesting that demand may be growing.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 130 euros, which is a price that has been reached in previous auctions for coins of similar condition. However, since the market can fluctuate, it is advisable to be prepared to adjust this figure based on competition in the auction and current demand.