To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Starting Price: 2000 euros.
2. Condition: The coin has a condition rating of 90 (XF), indicating that it is in very good shape. This generally increases its value compared to coins with lower conditions.
3. Auction History:
- It has been auctioned 3 times and sold on all occasions.
- The average hammer price in the past is 2983.33 euros, suggesting that buyers are willing to pay more than the starting price.
- Previous hammer prices were 1300 euros (with a condition of 80) and 1900 euros (also with a condition of 80). This indicates that the price can increase significantly with better condition.

Given that the condition of the current coin is superior to the previous ones, and considering the average hammer price, an estimated maximum purchase price could be set in a range above the previous average hammer price.

Estimated Maximum Purchase Price:
We could consider a hammer price that is in the range of 3000 to 3500 euros, given that the condition is better and the interest in the coin seems to be high.

Therefore, a reasonable maximum purchase price could be 3200 euros.