To estimate a maximum purchase price for the coin in question, we will 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. Historical Prices:
- The average hammer price in previous auctions is 450.57 euros, indicating that, in general, this coin has good market interest.
- Previous hammer prices varied, but there are examples of auctions reaching up to 1000 euros (in the case of the March 2024 auction with a condition of 85).

3. Starting Price and Average Starting Price:
- The current starting price is 90 euros, which is relatively low compared to the average starting price of 179.38 euros. This suggests that there may be a buying opportunity at a reasonable price.

4. Sales Trends: The coin has sold every time it has been auctioned, indicating consistent demand.

5. Condition Comparison: A condition of 70 is lower than the conditions of 80 and 85 that have reached higher hammer prices. This suggests that the hammer price for this coin could be lower than the examples of higher condition.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 250 to 350 euros. This is based on the fact that, although the condition is not the best, the interest in the coin and historical prices suggest it could reach a reasonable price at auction.

Therefore, an estimated maximum purchase price could be 300 euros.