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

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in acceptable shape, but not in the best possible condition.

2. Price History:
- The average hammer price for this coin in the past is 203.89 euros.
- Previous hammer prices for coins with a similar condition (70) have varied, but some relevant prices can be observed:
- 170 euros (2020-12-16)
- 190 euros (2020-11-19)
- 140 euros (2020-10-20)
- 180 euros (2018-05-30)
- 180 euros (2018-10-15)

3. Price Trends:
- Hammer prices for coins with a condition of 70 have been in a range of approximately 140 to 190 euros in recent auctions.
- In auctions where the condition was better (80 or 85), hammer prices have been significantly higher, reaching up to 420 euros.

4. Starting Price: The current starting price is 175 euros, which is reasonable given the price history.

5. Maximum Price Estimate:
- Given that the average hammer price is 203.89 euros and considering that the condition is 70, a maximum purchase price could be set slightly above the average hammer price, but not so high as to risk paying more than what has been paid in the past for coins in similar conditions.

Based on this analysis, an estimated maximum purchase price for this coin could be 220 euros. This allows for some competition in the auction, while also remaining within a reasonable range based on the price history.