Based on the provided data, we can observe that the coin in question has a conservation grade of 80 (MBC+), indicating that it is in fairly good condition. Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices.

The average starting price for this coin has been 430 euros, while the average final price has been 511.5 euros. In previous auctions, estimated prices have ranged from 200 to 1100 euros, with conservation grades ranging from 70 to 85.

Given that the coin will be auctioned soon and considering the previous prices as well as the current conservation grade of the coin, we could estimate a maximum purchase price around 1000 euros. However, it is important to note that the final auction price may vary depending on the demand at the auction and other factors that may influence buyers' decisions.