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

1. Current Condition: The coin has a condition rating of 70 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for similar coins has been 51 euros.
- In previous auctions, hammer prices have varied, with a maximum of 220 euros in an auction where the condition was 90.
- Coins in condition 80 have reached hammer prices of up to 50 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, and the average starting price in the past has been 29.88 euros.

4. Sales Trends: The coin has been auctioned 24 times, of which it has sold 23 times, indicating high demand.

5. Previous Estimates: In past auctions, the estimated price has ranged from 30 to 100 euros, depending on the condition.

Given that the coin's condition is 70, which is an acceptable state, and considering the hammer price history, an estimated maximum purchase price could be around 60-70 euros. This is based on the fact that, although the condition is not the highest, there is a price history suggesting that coins in similar conditions have reached hammer prices in that range.

Therefore, an estimated maximum purchase price for this coin could be 70 euros.