To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the auction history and hammer prices.

1. Current Condition: The coin has a condition of 80 (VF+), indicating that it is in fairly good shape, but not the best possible condition.

2. Price History:
- The average hammer price in the past is 541.07 euros.
- The hammer prices in previous auctions for coins with similar conditions (75-85) have varied, but some examples are:
- 395 euros (condition 85)
- 460 euros (condition 75)
- 420 euros (condition not specified)
- 650 euros (condition not specified)
- 380 euros (condition 75)

3. Price Trends:
- The overall trend shows that coins with similar conditions have reached hammer prices ranging from 380 to 650 euros.
- The most recent auction with a condition of 90 reached a hammer price of 460 euros, suggesting that condition has a significant impact on price.

4. Estimation:
- Given that the condition of the coin is 80 (VF+), and considering the price history, a reasonable hammer price could be in the range of 400 to 600 euros.
- However, since the average hammer price is 541.07 euros, and considering that the coin has a starting price of 250 euros, a maximum purchase price could be slightly higher than the average, but not so much as to risk paying more than what has been paid in the past.

Conclusion: An estimated maximum purchase price for this coin could be approximately 600 euros. This is based on the price history and the current condition of the coin.