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

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in fairly good shape, although not the best possible condition.

2. Auction History:
- The average hammer price for this coin in the past is 1470.07 euros.
- The last auction for this coin had a hammer price of 2100 euros with a condition rating of 95, indicating that coins in better condition can reach significantly higher prices.
- Overall, hammer prices have varied, but the trend seems to be that coins in better condition (like those rated 95) have achieved higher prices.

3. Starting Price: The current starting price is 1500 euros, which is a good starting point.

4. Comparison with Previous Prices:
- In previous auctions, coins with similar condition (80) have had hammer prices ranging from 1100 to 1700 euros, depending on demand and other factors.

5. Market Trends: Given that the coin has sold in all previous occasions and considering that there is a scheduled auction, demand may influence the price.

Based on these factors, an estimated maximum purchase price could be around 1800-2000 euros, considering that the condition is good and there is interest in the coin. This allows for some margin for competition in the auction, but it is also based on the history of hammer prices.