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 80 (MS+), indicating that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By looking at previous auction prices, we can see that the coin has reached auction prices of up to 260 euros in past sales, although this may depend on the condition of the coin at those times.

3. Average Auction Price: The average auction price for this coin is 118.59 euros, which provides a useful reference.

4. Starting Price and Estimated Price: The current starting price is 75 euros, and the estimated price is 150 euros. This suggests that there are expectations for the coin to sell at a higher price than the starting bid.

5. Auction Trends: The coin has been auctioned 36 times, with a sell-through rate of 97.2% (35 out of 36). This indicates a consistent interest in the coin.

Given all this, a reasonable maximum purchase price could be in the range of 150 to 200 euros, considering that the estimated price is 150 euros and that it has previously reached higher auction prices. However, since the condition is good and there is interest in the coin, a maximum purchase price of 200 euros could be a prudent estimate.