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

1. Coin Condition: The coin has a condition of 70 (MS-), indicating that it is in acceptable shape, but not of high quality. This generally affects the price, as coins in better condition tend to fetch higher prices.

2. Previous Auction Prices: By observing the auction prices of coins with similar conditions (around 70), we can see that prices vary. For example, in previous auctions, coins with a condition of 70 have reached hammer prices of up to 20-30 euros, while others with higher conditions have achieved significantly greater prices.

3. Average Hammer Price: The average hammer price for this coin is 84.28 euros, suggesting that, in general, coins of this reference can reach higher prices, but this also depends on the condition.

4. Market Trends: Since the coin has been auctioned 145 times and has had a sell-through rate of 91%, this indicates a consistent interest in this coin, which can influence the price.

5. Starting Prices and Estimates: The starting price is 15 euros, and the average starting price is 55.23 euros. This suggests that the market is willing to pay more than the starting price on many occasions.

Based on these factors, an estimated maximum purchase price for this coin, considering its condition and market interest, could be between 30 and 50 euros. This is based on the analysis of previous prices and market trends for coins of similar condition.