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 75 (MBC), indicating that it is in an acceptable state, but not among the best qualities.

2. Auction History:
- The average hammer price in previous auctions is 104.73 euros.
- The coin has been auctioned 13 times, of which it has sold 11 times, indicating good demand.
- Previous hammer prices for coins with a similar condition (70-80) have varied, but there are examples of auctions reaching up to 190 euros for coins in condition 70.

3. Starting Price and Average Starting Price:
- The current starting price is 80 euros, and the average starting price in the past has been 85 euros.

4. Price Trends:
- In previous auctions, hammer prices have ranged from 38 euros to 190 euros, depending on the condition and demand at that time.

Given that the coin's condition is 75 and considering the price history, an estimated maximum purchase price could be in the range of 120 to 150 euros. This is based on the fact that, although the condition is not the highest, there is a history of hammer prices suggesting that buyers are willing to pay more for coins in similar conditions.

Therefore, a reasonable estimated maximum purchase price could be 150 euros.