Based on the provided data, we can see that the coin in question has a grade of 70 (MBC-), with a starting price in the current auction of 30 euros. In the past, this same coin was auctioned once, with a starting price of 300 euros, an estimated price of 500 euros, and a final price of 1000 euros, with a grade of 80.

Considering that the coin will be auctioned once again in the coming days, and taking into account the average starting price of 165 euros and the average final price of 1000 euros, as well as the previous final price of 1000 euros, we can estimate a maximum purchase price for this coin in the current auction.

Given that the grade of the coin is 70 (MBC-), which is lower than the grade in the previous auction (80), and considering the starting price of 30 euros, we could estimate a maximum purchase price in the range of 500 to 700 euros, considering the upward trend in final prices and the slightly lower grade on this occasion.

Therefore, an estimated maximum purchase price for this coin in the current auction could be around 500 to 700 euros.