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

1. Current Condition: The coin has a condition rating of 80 (MS+). This is an important factor, as coins in better condition tend to reach higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 1500 euros. In previous auctions, hammer prices have varied, but there are recent examples where coins with similar conditions have reached hammer prices of up to 2100 euros.

3. Price Trends: In recent years, hammer prices have shown an upward trend, especially for coins in good condition. For example, in recent auctions, coins with a condition rating of 95 have reached hammer prices of 1800 to 2400 euros.

4. Average Hammer Price: The average hammer price for this coin is 1217.23 euros, indicating that the hammer price may be higher than the starting price in recent auctions.

5. Comparison with Previous Prices: In previous auctions, coins with condition ratings of 90 to 95 have had hammer prices ranging from 1400 to 2100 euros. Given that the condition of this coin is 80, it is reasonable to expect that its hammer price will be below these values, but still within a competitive range.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 1800 and 2100 euros, considering that the condition and market trend are favorable. However, since the condition is 80, a more conservative price could be around 1700 euros.

Therefore, a reasonable estimated maximum purchase price could be 2000 euros.