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 has been 226.09 euros.
- In previous auctions, coins with a similar condition (30) have sold for prices ranging from 55 to 160 euros, with the last hammer price being 72 euros in January 2023.

3. Starting Price and Average Starting Price:
- The current starting price is 50 euros, which is relatively low compared to the average starting price of 140.53 euros for similar coins.

4. Sales Trends: The coin has been auctioned 42 times, of which 35 have resulted in sales. This indicates a consistent interest in the coin, which may influence the price.

5. Previous Estimates: In past auctions, the estimated price for coins with similar conditions has been up to 250 euros, although the actual hammer price has been lower.

Based on these factors, an estimated maximum purchase price for this coin could be between 70 and 120 euros, considering that the condition is not optimal and that the interest in the coin may not be high enough to reach the highest hammer prices. A price of 100 euros could be a good benchmark for a competitive offer.