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

1. Current Condition: The coin has a condition rating of 70 (MS-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for similar coins in the past has been approximately 285.79 euros.
- The coin has been auctioned 63 times, of which it has sold 59 times, indicating good demand.
- In previous auctions, hammer prices have varied, but there are examples of sales that have exceeded 360 euros (such as in the November 2020 auction).

3. Starting Price and Estimates:
- The current starting price is 300 euros, which is slightly higher than the average starting price of 234.1 euros.
- The estimated price for this auction is 300 euros, suggesting that the organizers expect considerable interest.

4. Recent Trends: In the most recent auctions, hammer prices have been in the range of 350 to 400 euros, indicating a growing interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 350 and 400 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. However, since the starting price is 300 euros, buyers may be willing to bid a little more, especially if there is interest in the coin.

Therefore, a reasonable maximum purchase price could be approximately 400 euros.