To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

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.

2. Previous Auction Prices: By looking at the auction prices of coins with a similar condition (70), we can see that the auction prices have varied. Some examples are:
- 50 euros (2020-12-14)
- 51 euros (2019-12-10)
- 60 euros (2023-05-23)
- 75 euros (2022-10-18)

3. Average Auction Price: The average auction price for this coin is 101.29 euros, but this includes coins of different conditions. For a condition of 70, it is likely that the auction price will be lower.

4. Price Trends: The current starting price is 30 euros, which suggests that the seller expects a lower auction price than the average. However, the average starting price is 61.44 euros, indicating that in the past, similar coins have had a higher starting price.

5. Estimation: Given that the condition is 70 and considering the previous auction prices, an estimated maximum purchase price could be between 50 and 75 euros. This is based on the previous auction prices for coins with a similar condition.

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