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 (EF-), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Starting Price and Average Hammer Price: The starting price is 90 euros, and the average hammer price in previous auctions is 111.28 euros. This suggests that, on average, similar coins have sold for above the starting price.

3. Sales History: The coin has been auctioned 134 times, of which 115 have resulted in sales. This indicates good demand and liquidity for this coin.

4. Previous Prices: By looking at previous hammer prices for coins with similar conditions (85 and 90), we can see that they have reached hammer prices that varied, but some have gone up to 140 euros or more in similar conditions.

5. Recent Trends: In the most recent auctions, hammer prices have shown an increase, which could indicate an upward trend in the value of this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 130 to 150 euros. This is based on the average hammer price and the price history of coins with similar conditions.

Therefore, a reasonable maximum purchase price could be 150 euros.