To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition of 70 (VF-), which indicates that it is in fairly good shape, but not among the best qualities. This may influence its value compared to coins of higher condition.

2. Auction History:
- In the past, this coin has been auctioned 5 times, of which it has sold 4 times. This indicates that there is interest in the coin.
- Previous hammer prices have been quite variable, with a maximum price of 150 euros and a minimum of 45 euros. This suggests that the price may fluctuate depending on demand at the time of the auction.

3. Starting Price and Average Prices:
- The current starting price is 30 euros, which is lower than the average starting price of 49 euros and the average hammer price of 97.5 euros. This could indicate that there is a buying opportunity at a relatively low price.

4. Comparison with Previous Prices:
- The last auction with a similar condition (75) had a hammer price of 120 euros. Given that the condition of the coin in question is lower, it is reasonable to adjust this price downward.

Taking all these factors into account, an estimated maximum purchase price could be around 80-90 euros. This is based on the auction price history, the current condition, and the demonstrated interest in previous auctions.