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

1. Condition: The coin has a condition of 70 (VF-), which indicates that it is in an acceptable state, but not excellent. This generally affects the price, as coins in better condition tend to reach higher prices.

2. Auction History:
- The coin has been auctioned 5 times in the past, of which it has sold 3 times. This suggests that there is interest in the coin, but also that there have been occasions when it did not sell.
- Previous hammer prices are relevant. For example, in 2011, prices were estimated at 450 and 300 euros, and in 2016, the estimated price was 403.91 euros. However, the most recent hammer price was 176.16 euros in 2021, indicating a possible decrease in interest or value of the coin.

3. Starting Price and Average Prices:
- The current starting price is 50 euros, which is significantly lower than the average starting price of 146.17 euros and the average hammer price of 238.08 euros. This could indicate that the seller is looking for a quick sale or that there is less interest in this particular auction.

4. Price Trends: Given that the most recent hammer price was 176.16 euros, this may be a good indicator of the current value of the coin.

Taking all these factors into account, an estimated maximum purchase price could be situated between the most recent hammer price and the average hammer price.

Therefore, a reasonable maximum purchase price could be around 180 to 200 euros. This reflects an interest in the coin, considering its condition and price history, but it is also conservative given the current starting price and the downward trend in hammer prices.