To estimate a maximum purchase price for the coin that will be auctioned, we can consider several factors based on the provided data:

1. Starting Price: The starting price is 50 euros.
2. Auction History: The coin has been auctioned 119 times, of which it has sold 100 times. This indicates good demand.
3. Average Hammer Price: The average hammer price in previous auctions is 47.27 euros, suggesting that, in general, coins of this reference sell close to their starting price.
4. Previous Prices: There are several previous hammer prices that varied significantly. For example, hammer prices of 120 euros and 140 euros have been recorded in recent auctions, indicating potential for higher prices.
5. Condition: There is no information about the condition of this coin, which may affect its value. However, in previous auctions, many coins in high condition (95 or more) have reached significant hammer prices.

Given that the starting price is 50 euros and considering the history of hammer prices, an estimated maximum purchase price could range between 80 and 120 euros, depending on the competition in the auction and the bidders' perception of the coin's quality.

Therefore, a reasonable estimated maximum purchase price could be 100 euros. This is based on the analysis of previous hammer prices and the demand observed in past auctions.