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

1. Current Condition: The coin has a condition rating of 85 (ebc-), indicating that it is in fairly good shape, but not among the highest qualities (FDC).

2. Auction History:
- The average hammer price for similar coins in the past has been 303.85 euros.
- Coins with a condition rating of 95 have reached hammer prices of up to 650 euros, while those with a condition rating of 85 have had hammer prices ranging between 150 and 320 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 150 euros, which is relatively low compared to the average hammer price.
- The average starting price of 187.37 euros also suggests that there is potential for an increase in the hammer price.

4. Sales Trends: The coin has been sold in 55 out of 61 auctions, indicating good demand.

5. Previous Prices: In previous auctions, coins with a similar condition have had hammer prices that varied, but they have generally sold for above the starting price.

Based on these factors, an estimated maximum purchase price for this coin could be between 250 and 300 euros, considering that the condition is an important factor and that there is a history of hammer prices supporting this estimate.

Therefore, a reasonable maximum purchase price could be approximately 280 euros.