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 80 (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 this coin in the past is 275.77 euros.
- The last auction of this coin with a similar condition (80) had a hammer price of 380 euros in May 2022.
- In other auctions, hammer prices have varied, but many have exceeded 200 euros, indicating consistent demand.

3. Starting Price and Estimates:
- The current starting price is 200 euros, which is reasonable given the price history.
- The estimated price in previous auctions has reached up to 400 euros, suggesting there is potential for a high hammer price.

4. Recent Trends: In the most recent auctions, hammer prices have shown an upward trend, which may indicate an increase in demand or in the coin's value.

Based on these factors, an estimated maximum purchase price for this coin could be between 350 and 400 euros, considering that the condition is good and that the price history supports this estimate. Therefore, a reasonable maximum purchase price could be 400 euros.