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

1. Coin 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 condition ratings.

2. Auction History:
- The average hammer price for similar coins is 145.61 euros.
- In previous auctions, coins with a similar condition (95) have reached hammer prices of up to 380 euros (as seen in the auction on 2021-03-18).

3. Starting Price: The current starting price is 900 euros, which is significantly higher than the average hammer price for similar coins. This may indicate that the seller has high expectations, but it could also suggest that the coin is particularly valuable or sought after.

4. Sales Trends: The coin has been auctioned 94 times, with an 88% sell-through rate (83 out of 94). This suggests that there is consistent interest in this coin.

5. Recent Hammer Prices: In the most recent auctions, hammer prices have varied, but the range has been from 20 to 900 euros, depending on condition and demand.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 500 euros, considering that the condition is high and there is a history of hammer prices that supports this estimate. However, given the starting price of 900 euros, it is possible that the seller is looking for a higher price, which could influence the purchasing decision.