Based on the data provided, we can observe that the coin in question has performed well in previous auctions, with final prices exceeding the starting price in most cases. The coin's condition is graded at 70 (MBC-), indicating it is in an acceptable state.

The average starting price in previous auctions has been 21.5 euros, while the average final price has been 43.4 euros. Additionally, in the last recorded auction, the coin fetched a final price of 85 euros.

Taking into account these data, along with the price history and condition of the coin, and assuming that demand for this coin remains stable, we could estimate a maximum purchase price around 90-95 euros. This estimation is based on the upward trend in final prices and the good condition of the coin. However, it is important to note that the final price in an auction can vary depending on demand and other market factors at the time of the auction.