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 average hammer price in previous auctions is 32 euros.
- Previous auctions with similar conditions (30) have had hammer prices that varied, but the last known hammer price for a condition of 30 was 30 euros.

3. Price Trends:
- Starting prices have varied, but the current starting price is 25 euros, which is consistent with previous starting prices.
- The estimated price in previous auctions has been up to 90 euros, but this refers to coins in better condition.

4. Supply and Demand: The coin has been auctioned 25 times, with a 72% sell-through rate, indicating moderate interest in the coin.

Taking these factors into account, an estimated maximum purchase price could be around 35-40 euros. This is based on the average hammer price and the price history of coins with similar conditions. However, since the condition is not high, it is wise not to exceed 40 euros to avoid overpaying.