Based on the data provided, we can see that the coin was auctioned once in the past with a starting price of 4000 euros and a conservation grade of 90 (EBC). The estimated price in that auction was 7000 euros. Given the high conservation grade (90), we can assume that the coin is in good condition.

Considering that the starting price this time is 3000 euros and the coin will be auctioned once again, we could estimate a maximum purchase price based on the previous estimated price and the conservation of the coin. Since the coin will be auctioned in the coming days, and considering that the average starting price is 3500 euros, we could consider a maximum purchase price of around 6500-7000 euros, taking into account the conservation and the previous estimated price.

It is important to note that the final auction price will depend on several factors, such as the demand at that specific time, the competition from other bidders, and the willingness of buyers to pay for the coin in question.