Based on the provided data, we can observe that the coin in question has had an average starting price in past auctions of 24.69 euros and an average closing price of 37.8 euros. Additionally, it has been auctioned a total of 29 times in the past, sold in 20 instances and unsold in 9 instances.

The current condition of the coin is 100 (UNC), indicating it is in excellent condition.

Analyzing the previous prices of this coin in past auctions, we can see that it has had price estimates ranging from 6 euros to 120 euros, showing a wide range of values.

Considering the upcoming auction of the coin and taking into account its price history, condition, and demand in previous auctions, an estimated maximum purchase price for this coin could be around 50-60 euros. This range is based on the average closing price in past auctions and previous price estimates. However, please note that the final auction price will depend on the demand and competition from other potential buyers at the time of the auction.