To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Starting Price: 30 euros, which is the initial price of the auction.
2. Condition: The coin has a condition rating of 70 (VF-), indicating that it is in fairly good shape, although not the best possible condition.
3. Auction History: The coin has been auctioned once before, with a hammer price of 190 euros. This suggests that there is significant interest in this coin, especially given its condition.
4. Average Starting and Hammer Prices: The average starting price is 52.5 euros, and the average hammer price is 190 euros. This indicates that, in general, coins of this reference tend to reach higher prices at auction.

Given that the coin has a condition rating of 70 and has previously reached a hammer price of 190 euros, it is reasonable to assume that interest in this coin will remain.

Taking all these factors into account, an estimated maximum purchase price could be in a range between the previous hammer price (190 euros) and a bit more, considering that the condition is good and there is an upcoming auction.

Therefore, an estimated maximum purchase price could be approximately 200-220 euros. This would allow for competitive bidding in the auction without exceeding a reasonable limit based on the price history.