To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 75 (MS), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins in condition 75 has been 68.05 euros.
- In previous auctions, the hammer price has varied, with some prices reaching up to 180 euros in a recent auction (2022-03-17) for a coin of similar condition.

3. Starting Price and Average Starting Price: The current starting price is 45 euros, and the average starting price in the past has been 42.2 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Sales Trends: The coin has sold in 23 out of the last 25 auctions, indicating good demand and consistent interest in this reference.

5. Maximum Price Estimate: Given that the average hammer price is 68.05 euros and considering that there have been exceptional sales reaching up to 180 euros, a reasonable maximum purchase price could be positioned between the average hammer price and the highest recorded price.

Taking all these factors into account, an estimated maximum purchase price for this coin could be approximately 80-100 euros. This reflects a balance between market interest, the coin's condition, and historical hammer prices.