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

2. Auction History: The coin has been auctioned 12 times in the past, with 8 successful sales. This suggests that there is consistent interest in the coin. The average hammer price in previous auctions is 96 euros, providing a good benchmark.

3. Previous Starting and Hammer Prices: By observing the starting and hammer prices from previous auctions, we note that the hammer price has varied, but generally, coins with similar conditions have reached hammer prices ranging from 60 to 200 euros, depending on the condition and demand at that time.

4. Current Starting Price: The starting price is 50 euros, which is relatively low compared to the previous average hammer price.

5. Price Trends: In the most recent auction, the coin sold for 50 euros, indicating that interest may have decreased, but it could also be an opportunity to acquire it at a lower price.

Taking all these factors into account, an estimated maximum purchase price could be around 100-120 euros, given that the condition is good and the price history suggests it could reach that range in a competitive auction. However, it is important to pay attention to demand at the time of the auction, as this can influence the final price.