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

1. Current Condition: The coin has a condition of 30 (BC+), which indicates that it is not in very good shape. This generally reduces its value compared to coins in better condition.

2. Auction History: By observing the hammer prices of coins with different levels of condition, we can see that coins in much better conditions (such as 70, 80, 85, 90, and 95) have reached significantly higher prices. For example:
- A coin with a condition of 70 has sold for a hammer price of up to 35 euros.
- A coin with a condition of 95 has sold for up to 450 euros.

3. Average Hammer Price: The average hammer price for this coin in the past has been 94.47 euros, but this includes coins in better conditions.

4. Recent Trends: In the most recent auctions, the hammer prices for coins with similar conditions have varied, but they have generally remained in a low range due to the condition.

Given that the condition of this coin is 30 (BC+), and considering the hammer price history of coins in similar conditions, an estimated maximum purchase price could be in the range of 10 to 20 euros. This is based on the fact that coins in lower conditions tend to sell for much lower prices than those in better condition.

Therefore, an estimated maximum purchase price for this coin could be 15 euros.