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

1. Current Condition: The coin has a condition of 85 (ebc-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Prices: By looking at previous auction prices for coins with similar conditions, we can see that:
- In recent auctions, coins with a condition of 85 have reached hammer prices of up to 20 euros.
- In earlier auctions, coins with conditions of 90 and 95 have reached hammer prices of 40 to 80 euros.

3. Average Hammer Price: The average hammer price for this particular coin is 83.43 euros, suggesting that, in general, coins of this reference tend to sell for relatively high prices.

4. Starting Price: The current starting price is 12 euros, which is quite low compared to previous hammer prices.

5. Sales Trends: The coin has been auctioned 44 times, of which 29 have resulted in sales. This indicates a consistent interest in the coin, which may influence its price.

Taking all these factors into account, an estimated maximum purchase price for this coin, considering its condition and previous hammer prices, could be in the range of 20 to 40 euros. This is based on the fact that coins with a similar condition have reached hammer prices in that range in the past. However, given the interest in the coin and its condition, a reasonable maximum purchase price could be 30 euros.