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

1. Starting Price: 150 euros.
2. Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in good shape, which may increase its value.
3. Auction History: It has been auctioned 2 times in the past, of which it sold once and did not sell once. This suggests that there is interest in the coin, but also that there may be some resistance in the price.
4. Average Starting and Hammer Price: The average starting price is 135 euros and the average hammer price is 160 euros. This indicates that, generally, coins of this reference tend to sell around those prices.
5. Previous Hammer Price: In the 2014 auction, the coin sold for 160 euros, establishing a precedent for its value.

Given that the condition is good and the previous hammer price was 160 euros, an estimated maximum purchase price could be in the range of 160 to 180 euros, considering that interest in the coin may have increased since then and that the condition is favorable.

Therefore, an estimated maximum purchase price could be 170 euros. This allows for some margin for competition in the auction, but it is also based on historical data and the current condition of the coin.