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

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 in the past is 84.28 euros.
- Previous auctions of this coin have shown hammer prices that vary, but some have reached up to 300 euros in exceptional conditions (such as the March 2020 auction with a condition rating of 95).

3. Starting Price and Average Starting Price:
- The current starting price is 18 euros, and the average starting price in the past is 40.24 euros. This suggests that the current starting price is relatively low compared to the historical average.

4. Sales Trends:
- Out of the 50 times it has been auctioned, it has sold on 41 occasions, indicating good demand.

5. Previous Estimates:
- In previous auctions, the estimated price has varied, but generally, coins with a similar condition have had estimates ranging between 50 and 100 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 80 to 120 euros. This range takes into account the current condition, the auction price history, and the demand observed in previous auctions.