Based on the provided data, we can observe that the coin in question had a starting price of 50 euros in the most recent auction, with a conservation grade of 80 (MBC+). Additionally, it has been auctioned a total of 19 times in the past, being sold in 15 instances and not sold in 4 instances.

The average starting price of previous auctions has been 98.16 euros, while the average final price has been 114.14 euros. Looking at the past prices of the coin, we can see that they have varied widely over the years, with estimates ranging from 15 euros to 400 euros.

Given that the coin will be auctioned soon and considering its price history, conservation, and demand, as well as the fact that it is expected to be auctioned only once more in the coming days, we could estimate a maximum purchase price around 120-140 euros. This takes into account the upward trend in final prices and the relatively good conservation of the coin. However, it is important to note that the final price will depend on the competition in the auction and other external factors.