To estimate a maximum purchase price for the coin in question, we can 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 generally reduces its value compared to coins in better condition.

2. Auction History:
- The average hammer price in previous auctions is 83.06 euros.
- The coin has been auctioned 37 times, of which it has sold 33 times, indicating good demand.
- In previous auctions, the hammer price has varied, but there are examples of sales reaching up to 290 euros in more favorable conditions.

3. Starting Price and Average Starting Price:
- The current starting price is 45 euros, and the average starting price in the past is 54.08 euros. This suggests that the current starting price is reasonable.

4. Recent Trends: In the most recent auctions, hammer prices have been higher, especially for coins in better condition. However, given that the condition of this coin is lower, it is likely that the hammer price will not reach the highest levels.

Taking all these factors into account, an estimated maximum purchase price could be around 70-80 euros. This is based on the average hammer price and price history, adjusted for the current condition of the coin.