Based on the data provided, we can observe that the coin in question has had an average auction closing price of 73.53 euros in previous auctions. Additionally, its current condition is 70 (VF+), indicating that it is in an acceptable but not excellent condition.

Considering that the average closing price has been 73.53 euros and the current condition is 70, we could estimate a maximum purchase price around 80-85 euros. Given that the coin has been auctioned 20 times in the past and has had good results in terms of closing price, it is reasonable to expect its value to remain in that range.

Therefore, my recommendation would be to consider a maximum purchase price of around 80-85 euros for this coin in the next auction.