Based on the information provided, we know that the coin will be auctioned with a conservation grade of 80 (MBC+), with a starting price of 110 euros. Since there have been no previous sales of this coin, we do not have a previous average auction price for this specific reference.

Considering that the conservation is good but not excellent, and the starting price is 110 euros, we could estimate a maximum purchase price around 20% above the starting price. Therefore, an estimated maximum purchase price for this coin at the auction could be around 132 euros.

It is important to note that this is just an estimate based on the information provided and general considerations about coin auctions. The final auction price may vary depending on demand and other factors at the auction.