Based on the provided data, we can observe that the coin in question had a starting price of 18 euros in the most recent auction and is in a conservation grade of 80 (MBC+). Additionally, it has been auctioned a total of 73 times in the past, with an average closing price of 51.17 euros.

Some of the previous prices for this coin have ranged between 18 and 100 euros, with price estimates ranging from 30 to 150 euros. Considering these data points, the current conservation grade of the coin, and the fact that it has been auctioned multiple times, we could estimate a maximum purchase price around 90 euros.

It is important to note that the final auction price may vary depending on factors such as demand at that specific time, competition from other bidders, and buyers' perception of the coin's value at that moment.