To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins in lower condition.

2. Auction History:
- The average hammer price for this coin in the past is 326.03 euros.
- The last auction for this coin had a starting price of 300 euros, suggesting that the market is willing to pay close to this price.
- In previous auctions, hammer prices have varied, but there are examples of sales exceeding 500 euros, especially for coins in better condition.

3. Price Trends:
- In recent auctions, hammer prices have shown a trend of being in the range of 300 to 600 euros, depending on the condition and demand at the time of the auction.

4. Average Starting Price: The average starting price of 153.11 euros suggests that, in general, coins of this reference do not usually go to auction at very high prices, but the hammer price is significantly higher.

Based on these factors, an estimated maximum purchase price for the coin in question could be in the range of 400 to 500 euros. This is due to its good condition and the hammer price history indicating that collectors are willing to pay more for coins in similar conditions.