Based on the provided data, we can see that the coin was previously auctioned with a starting price of 30 euros and an estimated price of 50 euros, with a grade of 70 (MBC-). Since the coin has been auctioned twice in the past and has been sold once, we can consider that it has some demand in the market.

The average starting price of the coin is 45 euros, while the average auction price has been 200 euros in the past. This indicates that there is a potential for an increase in the auction price compared to the starting price.

Considering the grade of the coin (70 - MBC-), its auction history, the previous average auction price, and the fact that it will be auctioned in euros, we could estimate a maximum purchase price of around 60-70 euros for this coin in the upcoming auction. It is important to note that the final price may vary depending on the demand at the time of the auction and other market factors.