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-). This indicates that it is in an acceptable state, but not of high quality. Coins with a similar condition have had auction prices that vary, but are generally below the auction prices of coins in better condition.

2. Auction History:
- The average hammer price for similar coins in condition 70 has been approximately 20-40 euros in recent auctions.
- In the past, coins with condition 70 have reached hammer prices of up to 40 euros, as seen in the auction on 2020-10-20.

3. Starting Price and Average Hammer Price:
- The current starting price is 15 euros, which is reasonable given the history of starting and hammer prices.
- The average hammer price for similar coins is 109.69 euros, but this includes coins in better condition.

4. Recent Trends:
- In the most recent auctions, hammer prices for coins with similar condition have been in the range of 20-30 euros.

Based on these factors, an estimated maximum purchase price for the coin in condition 70 could be between 30 and 40 euros. This is because, although the average hammer price is higher, the condition and price history suggest that a more conservative range is more appropriate.

Maximum Purchase Estimate: 40 euros.