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

1. Current Condition: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: Looking at previous hammer prices for coins with similar conditions:
- In recent auctions, coins with a condition of 95 have reached hammer prices of up to 110 euros.
- The average hammer price for coins with a condition of 95 has been around 70-90 euros on several occasions.

3. Starting Price and Average Hammer Price: The starting price is 30 euros, and the average hammer price is 42.13 euros. However, given that the condition of this coin is high, it is reasonable to expect that the hammer price will be significantly higher.

4. Market Trends: Since the coin has been auctioned 172 times and has a good sales history (138 times), this suggests that there is consistent interest in this coin, which may increase its value at auction.

Based on these factors, an estimated maximum purchase price for this coin could be between 90 and 120 euros, considering that the condition is high and there have been precedents for hammer prices in that range.

Therefore, a reasonable maximum purchase price could be 100 euros.