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

1. Current Condition: The coin has a condition rating of 90 (EF), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 3590 euros.
- The last auction with a similar condition (90) had a hammer price of 5800 euros.
- There are examples of previous auctions with conditions of 85 and 95 showing hammer prices ranging from 2600 to 5800 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 3000 euros, which is below the average starting price of 3190. This may indicate that there is a buying opportunity at a reasonable price.

4. Sales Trends: The coin has been sold in 10 out of 13 auctions, suggesting that there is demand for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 4000 to 5000 euros. This is based on the average hammer price and the fact that the coin's condition is good. However, since the starting price is 3000 euros, it may be possible to acquire it for a lower price if competition in the auction is not high.

Therefore, a reasonable maximum purchase price could be 4500 euros.