To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition of 50 (fine), which indicates that it is not in the best condition. This will negatively affect its value compared to coins in better condition.

2. Auction History:
- The coin has been auctioned 6 times, of which it has sold 5 times. This indicates a consistent interest in the coin.
- Previous hammer prices are quite high, especially the one from 2013, where it sold for 22,509.25 euros with a condition of 90. This suggests that, in optimal conditions, the coin can reach very high prices.
- However, hammer prices for lower conditions (such as 75 and 80) are significantly lower, indicating that condition is a crucial factor in pricing.

3. Starting Price and Average Price:
- The current starting price is 1,000 euros, which is relatively low compared to the average hammer price of 6,558.04 euros. This suggests that there is potential for the hammer price to be higher, but it also depends on the condition.

4. Comparison with Previous Prices:
- In previous auctions, starting prices have varied, but the lowest hammer price was 1,200 euros (in 2014), indicating that even in non-optimal conditions, the coin has a minimum value.

Given all this, and considering that the current condition is 50, an estimated maximum purchase price could be set in a more conservative range.

Estimated Maximum Purchase Price: It could be reasonable to estimate a maximum purchase price around 2,500 to 3,000 euros, taking into account the condition and price history. This would allow for a profit margin if the coin is resold in the future, especially if its condition improves or if the market becomes more favorable.