Based on the information provided, we know that the coin has a grade of 80 (MBC+), a starting price of 250 euros, and has not been auctioned in the past. Given that the grade is quite good but not excellent, and it is the first time being auctioned, we can consider the starting price to be reasonable.

Considering the good but not excellent grade and the starting price of 250 euros, we could estimate a maximum purchase price around 300-350 euros, taking into account that it is the first time being auctioned and there are no previous auction data. It is important to note that the final price will depend on the demand at the auction and the willingness of potential buyers to bid on the coin.