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

1. Current Condition: The coin has a condition rating of 30 (BC+), indicating that it is not in the best condition. This may affect its value compared to coins in better condition.

2. Auction History:
- The coin has been auctioned 8 times, of which it has sold 7 times. This indicates good demand.
- The average hammer price in previous auctions is 80.71 euros, providing an important benchmark.
- In previous auctions, hammer prices have varied significantly, ranging from 17 euros to 160 euros, depending on condition and other factors.

3. Starting Price and Estimates:
- The current starting price is 30 euros, which is below the historical average hammer price. This may indicate a buying opportunity.
- The average starting price in previous auctions is 44.11 euros, suggesting that the current starting price is competitive.

4. Price Trends:
- In the most recent auction (2022), a coin with a condition rating of 25 was estimated at 60 euros, suggesting that even coins in similar conditions can reach higher prices.

Taking all these factors into account, an estimated maximum purchase price could be around 70-80 euros. This is based on the historical average hammer price and the demand observed in previous auctions, adjusted for the current condition of the coin.