Based on the data provided, we can observe that the coin in question has had a starting price in the current auction of 18 euros, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices.

The average starting price of this coin in previous auctions has been 62 euros, while the average final price has been 165.11 euros. The coin has been sold in 90% of previous auctions.

Considering the previous prices of this coin, as well as its current conservation grade, we can estimate a maximum purchase price. Given that the current starting price is 18 euros and the conservation grade is 30 (BC+), we can consider an estimated maximum purchase price around 50-60 euros, taking into account previous auction prices and the current conservation grade.

Therefore, an estimated maximum purchase price for this coin in the current auction could be around 50-60 euros. It is important to note that this is only an estimate based on the provided data and historical information from previous auctions.