Based on the provided data, we can observe that the coin in question has had an average auction closing price of 155.17 euros in previous auctions. Additionally, its current condition is 85 (ebc-).

Considering that the starting price for the next auction is 75 euros and the average starting price in previous auctions has been 134 euros, we could estimate that the closing price of this coin in the next auction could be around 155-160 euros.

Given that the coin's condition is quite good (85 ebc-) and considering its past successful auction results, we could expect the closing price to fall within the range of 155-160 euros.

Therefore, my estimate for the maximum purchase price for this coin in the next auction would be around 160 euros.