Based on the data provided, we can observe that the coin in question has had quite variable starting and closing prices in previous auctions. The current condition of the coin is estimated at 30 (BC+), indicating that it is not in the best condition, but also not in the worst.

The average starting price in previous auctions was 53.56 euros, while the average closing price was 74.14 euros. However, it is important to note that these values can vary significantly depending on factors such as demand at the time of the auction and the condition of the coin.

Given that the coin has been auctioned 9 times in the past and sold in 7 of those instances, we can infer that there is market interest in this reference.

Taking all these factors into consideration, and considering that the current condition is 30 (BC+), the estimated maximum purchase price for this coin in the next auction could be around 90-100 euros. It is important to note that this is just an estimate and the final price could vary depending on various factors at the time of the auction.