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 75 (MBC), indicating that it is in quite good shape. This suggests that its value should be in a medium-high range.

2. Previous Prices: Looking at previous auction prices for coins with a similar condition (75), the highest auction price was 80 euros in 2020. However, there are also more recent auctions showing higher prices, such as 130 euros in 2021 for a coin with a condition of 80.

3. Average Auction Price: The average auction price for this coin is 105.72 euros, indicating that, in general, coins of this reference tend to sell for relatively high prices.

4. Recent Trends: In the most recent auctions, the hammer prices have shown an increase, with auctions of 140 euros and 210 euros for coins of similar condition.

5. Starting Price: The starting price is 45 euros, which is relatively low compared to previous hammer prices.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 120 to 150 euros, considering that the condition is good and there is an upward trend in auction prices in recent sales.

Therefore, a reasonable estimated maximum purchase price could be 130 euros.