To estimate a maximum purchase price for the coin in question, we can consider several factors:

1. Current Condition: The coin has a condition of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins in lower condition.

2. Current Listing Price and Previous Prices: The current listing price is 140 euros, and the average hammer price in previous auctions is 169.32 euros. This suggests that, in general, coins of this reference tend to sell for above their listing price.

3. Sales History: The coin has been auctioned 27 times, of which 26 have been sold. This indicates good demand and sustained interest in this coin.

4. Recent Hammer Prices: In the most recent auctions, the hammer prices have been quite high, such as 240 euros in March 2023 and 220 euros in October 2022. This suggests that interest in the coin has increased, especially in good condition.

5. Price Trends: Looking at the hammer prices of coins with similar conditions (80), the price range has varied, but the hammer prices have been in the range of 120 to 240 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 240 euros, considering that interest in the coin seems to be increasing and that its condition is good. Therefore, a reasonable maximum purchase price could be 220 euros.