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 of 80 (MBC+), indicating that it is in relatively good shape. This suggests that its value should be in the upper range of coins with a similar condition.

2. Starting Price and Average Hammer Price: The starting price is 100 euros, and the average hammer price in previous auctions is 240.53 euros. This indicates that, generally, coins of this reference tend to sell for significantly higher prices than their starting price.

3. Sales History: The coin has been auctioned 69 times, of which 61 have been sold. This suggests good demand and sustained interest in this coin.

4. Previous Prices: Looking at previous hammer prices for coins with a similar condition (80), we can see that they have reached hammer prices of up to 155 euros in recent auctions. However, there are examples of coins with higher conditions that have reached much higher prices, such as 950 euros in a previous auction with a condition of 95.

5. Recent Trends: In the most recent auctions, hammer prices for coins with a condition of 80 have been in the range of 155 euros, suggesting that this could be a good benchmark.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 150 to 200 euros. This takes into account the current condition, the price history, and the trend of hammer prices in recent auctions.