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 observing 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)
- 70 euros (2023-03-22)

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, the auction price tends to be lower.

4. Starting Price: The starting price is 30 euros, which suggests that the seller expects a lower price than the average auction price.

5. Price Trends: In previous auctions, coins with a condition of 70 have reached auction prices ranging from 50 to 70 euros.

### Maximum Purchase Price Estimate
Given that the condition is 70 and considering the previous auction prices, a reasonable maximum purchase price could be in the range of 60 to 70 euros. This is based on the analysis of previous auction prices and the current condition.

Estimated Maximum Purchase Price: 70 euros.