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 quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for coins of this reference is 89.5 euros.
- In previous auctions, we have seen hammer prices that varied significantly, from 28 euros to 140 euros, depending on the condition and other factors.

3. Starting Price: The current starting price is 120 euros, suggesting that the seller has high expectations for this auction.

4. Price Trends: In past auctions, coins with a similar condition (70) have reached hammer prices of up to 140 euros. This suggests that there is a market willing to pay higher prices for well-preserved coins.

5. Supply and Demand Analysis: Given that this coin has been auctioned 12 times in the past and has sold 10 of those times, there is a consistent interest in this reference, which may increase its value.

Based on these factors, an estimated maximum purchase price could be in the range of 130 to 150 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. However, since the starting price is 120 euros, it is likely that buyers will be willing to bid up to that range to secure the coin.