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

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices:
- The average hammer price for this coin has been 167.45 euros.
- Previous hammer prices in similar conditions (condition 70-80) have ranged between 130 and 200 euros.

3. Current Starting Price: The starting price is 150 euros, which is a good starting point, but does not necessarily indicate the final hammer price.

4. Sales Trends: The coin has been auctioned 12 times, of which 11 have been sold. This suggests good demand and consistent interest in the coin.

5. Previous Estimates: Estimated prices in previous auctions have varied, but some have reached up to 250 euros in similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 180 to 220 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 200 euros.