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 similar coins has been 541.79 euros.
- In previous auctions, coins with a similar condition (80) have reached hammer prices that varied, but some examples are:
- 270 euros in March 2020.
- 300 euros in February 2020.
- 460 euros in April 2022.
- 650 euros in October 2022.

3. Starting Price and Average Starting Price: The current starting price is 200 euros, and the average starting price in the past has been 208.55 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Recent Trends: In the most recent auctions, hammer prices have been significantly higher than the starting price, indicating increasing demand.

Based on these factors, an estimated maximum purchase price could be in the range of 500 to 700 euros, considering that the average hammer price has been 541.79 euros and that there are examples of recent auctions exceeding 600 euros.

Therefore, a reasonable maximum purchase price could be 650 euros.