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

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

2. Previous Auction Prices: By observing the hammer prices of coins with a similar condition (30) in previous auctions, we can see that:
- On several occasions, coins with a condition of 30 have sold for prices ranging between 80 and 160 euros.
- The average hammer price for coins with a condition of 30 seems to be in the range of 100-120 euros.

3. Starting Price and Average Hammer Price: The current starting price is 60 euros, and the average hammer price in previous auctions is 156.86 euros. This suggests that there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, the hammer prices for coins with a condition of 30 have shown a range of 120 to 160 euros, indicating that there is interest in this type of coin.

Based on these factors, an estimated maximum purchase price for this coin could be around 120-140 euros, considering that the condition is not optimal and that interest in the coin may vary.

Therefore, a reasonable maximum purchase price could be 130 euros.