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

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

2. Previous Hammer Prices:
- The coin has had hammer prices that vary significantly, ranging from 180 to 850 euros, depending on the condition and other factors.
- The hammer prices closest to the current condition (70) are:
- 180 euros (2020-10-21)
- 220 euros (2021-10-20)
- 300 euros (2024-02-14)
- 320 euros (2022-03-17)
- 350 euros (2024-12-11)

3. Average Hammer Price: The average hammer price is 361.67 euros, indicating that, in general, coins of this reference tend to sell for relatively high prices.

4. Starting Price: The current starting price is 180 euros, which is a reasonable starting point.

5. Auction Trends: Given that the coin has been auctioned 13 times and has had a high sales percentage (12 out of 13), this suggests there is consistent interest in this coin.

### Estimation of Maximum Purchase Price:
Taking all these factors into account, a reasonable maximum purchase price could be in the range of 300 to 400 euros, given that:
- The condition is 70, which limits the price compared to coins in better condition.
- Previous hammer prices for coins with similar condition have reached up to 350 euros.
- The average hammer price is 361.67 euros, suggesting that buyers are willing to pay more at auctions.

Therefore, an estimated maximum purchase price could be 350 euros. This allows for a margin for competition in the auction, considering that interest in the coin is high.