To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 80 (VF+), indicating that it is in acceptable shape, but not of the highest quality. This may influence the price, as coins in better condition tend to fetch higher prices.

2. Previous Auction Prices:
- In previous auctions, we have seen hammer prices that varied significantly. For example:
- In 2023, a coin with a condition of 95 was sold for 4200 euros.
- In 2022, a coin with a condition of 90 was sold for 700 euros.
- In 2021, a coin with a condition of 80 was sold for 500 euros.
- In 2019, a coin with a condition of 80 was sold for 460 euros.

3. Price Trends:
- The average hammer price for similar coins seems to be around 1066.07 euros, suggesting that, in general, coins of this reference tend to reach higher prices than the starting price.

4. Starting Price: The starting price is 500 euros, which is a good starting point, but since all coins of this reference have sold in the past, it is reasonable to expect that the hammer price will be above the starting price.

5. Estimation: Given that the condition is 80 and considering the previous hammer prices, an estimated maximum purchase price could be in the range of 600 to 800 euros. This is based on the fact that coins with similar conditions have reached hammer prices in that range.

Therefore, an estimated maximum purchase price for this coin could be 800 euros.