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

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in an acceptable state, but not excellent. This may influence the price, as coins in better condition tend to fetch higher prices.

2. Current Listing Price and Previous Prices: The current listing price is 75 euros, and the average hammer price in previous auctions is 151.88 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their listing price.

3. Sales History: Out of the 10 times it has been auctioned, it has sold 8 times, indicating good demand. Additionally, the average hammer price in previous auctions is a good indicator of what buyers are willing to pay.

4. Comparison with Previous Prices: Looking at previous hammer prices, we can see that in 2018 it sold for 280 euros in a condition of 90, and in 2014 it sold for 190 euros in a condition of 70. This suggests that the price can vary considerably depending on the condition and demand at the time of the auction.

5. Market Trends: Given that the average hammer price is 151.88 euros, and considering that the current condition is 70, an estimated maximum purchase price could be in a range that reflects both the condition and the price history.

Taking all these factors into account, an estimated maximum purchase price for this coin could be approximately 150-180 euros. This is based on the price history, current condition, and market trend.