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

1. Current Condition: The coin has a condition 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 in previous auctions is 1062.39 euros.
- It has been auctioned 39 times, of which 19 have been sold, indicating considerable interest in the coin.
- Previous hammer prices varied, but there are examples of auctions that have reached up to 3800 euros (in a condition of 90).

3. Starting Price and Average Starting Price:
- The current starting price is 100 euros, which is quite low compared to the average hammer price.
- The average starting price in the past has been 737.9 euros.

4. Price Trends:
- In previous auctions, prices have fluctuated considerably, but overall, hammer prices have been significantly higher than starting prices.

Given all this, and considering that the coin's condition is 70, an estimated maximum purchase price could be in the range of 800 to 1200 euros. This is based on the average hammer price and the demonstrated interest in previous auctions, as well as the current condition of the coin.

Therefore, an estimated maximum purchase price could be approximately 1200 euros.