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 hammer prices of coins with similar conditions (70 and 75), we can see that the hammer prices have varied. For example, in previous auctions, coins with a condition of 70 have reached hammer prices ranging from 42 to 66 euros.

3. Average Hammer Price: The average hammer price for this coin is 97.71 euros, but this may be influenced by coins in better condition.

4. Starting Price: The starting price is 30 euros, which may attract more bidders, but the final price will depend on the competition in the auction.

5. Market Trends: Since the coin has been auctioned 172 times and has had a good number of sales (144), this suggests that there is a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 70 to 90 euros. This is based on the analysis of previous hammer prices for coins of similar condition and the general interest in the coin.