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 fairly good shape, but not the best possible condition.

2. Current Starting Price and Previous Prices: The current starting price is 90 euros, and the average starting price in previous auctions is 125.57 euros. This suggests that the current starting price is relatively low compared to the historical average.

3. Previous Hammer Prices: The average hammer price in previous auctions is 187.3 euros. This indicates that, in general, buyers are willing to pay significantly more than the starting price.

4. Recent Trends: In the most recent auctions, hammer prices have varied, but there are examples of hammer prices exceeding 200 euros for coins in similar conditions.

5. Demand and Supply: The coin has been auctioned 46 times in the past, with 39 sales, indicating good demand. Additionally, it will be auctioned in the coming days, which may increase competition and the price.

Taking all these factors into account, an estimated maximum purchase price could be between 200 and 250 euros. This is based on the average previous hammer price and the current condition of the coin. However, since the starting price is 90 euros, it may be possible to acquire it for a lower price if competition is not high.

Therefore, a reasonable maximum purchase price could be 220 euros.