Based on the data provided, we can observe that the coin in question has had an average auction closing price of 134.9 euros in previous auctions. Additionally, its condition has been maintained at a level of 80 (MBC+).

Considering that the starting price for the next auction is 90 euros and that the coin has performed well in previous auctions, we could estimate a maximum purchase price around 150-160 euros. This is based on the fact that the average auction closing price has consistently been higher than the starting price, and taking into account the condition of the coin.

It is important to note that the final auction price may vary depending on factors such as demand at that specific moment, the number of interested parties in the coin, and other elements that may influence the bidding.