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

1. Current Condition: The coin has a condition rating of 30 (BC+), which indicates that it is not in very good shape. This generally reduces its value compared to coins in better condition.

2. Historical Prices: By looking at previous auction prices, we can see that coins with similar conditions (although some are better) have had auction prices that vary. For example, in past auctions, the prices have ranged from 32 to 260 euros, depending on the condition and other factors.

3. Average Hammer Price: The average hammer price for this coin is 92.97 euros, but this includes coins in better condition. Given that the current condition is 30, it is likely that the hammer price will be below this average.

4. Starting Price: The starting price is 50 euros, which can be a good indicator of what is expected to be obtained at the auction.

5. Sales Trends: The coin has been auctioned 41 times, of which 35 have been sold. This indicates good demand, although the condition may affect the sale.

Taking all these factors into account, an estimated maximum purchase price could be between 50 and 70 euros, considering that the condition is not optimal and the starting price is 50 euros. A hammer price in the range of 60-70 euros could be reasonable, given the price history and demand.