Based on the data provided, we can observe that the coin in question has had an average auction closing price of 521 euros in previous auctions. The current condition of the coin is 80 (MBC+), indicating that it is in fairly good condition.

Considering that the starting price this time is 800 euros and the average starting price in previous auctions was 492.31 euros, we can see that the current starting price is significantly higher. However, taking into account that the coin has been sold in the past on several occasions and its condition is good, we could estimate a maximum purchase price around 600-650 euros.

It is important to note that the final auction price will depend on the demand at that specific moment, so it is advisable to pay attention to how the auction unfolds to adjust the offer accordingly.