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 (MBC+), indicating that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 334.14 euros.
- The coin has been auctioned 35 times, of which it has sold 30 times, indicating good demand.
- In previous auctions, the hammer price has varied, but there are examples of sales above 500 euros for coins with similar conditions.

3. Starting Price and Estimates:
- The current starting price is 300 euros, which is slightly higher than the average starting price of 250.48 euros.
- The estimated price for this auction is 450 euros, suggesting that sellers expect good interest in the coin.

4. Recent Trends:
- In the most recent auctions, hammer prices have ranged from 300 to 600 euros, depending on the condition.

Based on these factors, an estimated maximum purchase price could be in the range of 400 to 500 euros. This is because, although the condition is not the highest, demand and price history suggest that buyers are willing to pay a significant price for coins in good condition.

Therefore, a reasonable maximum purchase price could be 450 euros.