Based on the provided data, we can observe that the coin in question has had a starting price of 18 euros in this auction, with a conservation grade of 70 (MBC-). 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 36.6 euros, while the average final price has been 66.2 euros.

Taking into account the previous prices of this coin, its current conservation grade, and the fact that it has been auctioned multiple times with final prices higher than the current starting price, we could estimate a maximum purchase price around 90-100 euros.

It is important to consider that the final auction price will depend on the demand at that specific moment, so it is advisable to keep an eye on its evolution.