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 very good shape. This generally reduces its value compared to coins in better condition.

2. Auction History:
- The average hammer price for similar coins in the past is 87.13 euros.
- The coin has been auctioned 9 times, of which it has sold 8 times, indicating good demand.
- Previous hammer prices for coins with similar conditions (30) have varied, but there is a recent hammer price of 55 euros for a coin with a condition of 30.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, which is significantly lower than the average starting price of 96 euros for similar coins.

4. Price Trends:
- In previous auctions, hammer prices have varied, but there is a pattern that coins with similar conditions have reached hammer prices of up to 75 euros.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 50 to 70 euros. This is based on the hammer price history for coins with similar conditions and the demand observed in previous auctions.

Therefore, a reasonable maximum purchase price could be 65 euros.