To estimate a maximum purchase price for the coin with a grade of 80 (MS+), we can analyze historical data from previous auctions and consider several factors:

1. Grade: The grade of the coin in question is 80 (MS+). In the past, coins with a similar grade have had hammer prices that vary considerably, but they are generally found in a higher range than the current starting price.

2. Previous hammer prices: By observing the hammer prices of coins with a grade of 80, we find that they have reached hammer prices of up to 170 euros (as in the auction on December 11, 2019). However, there are also examples of lower prices, such as 55 euros in recent auctions.

3. Average hammer price: The average hammer price for this particular coin is 111.05 euros, indicating that, in general, coins of this reference tend to sell for above their starting price.

4. Recent trends: In the most recent auctions, hammer prices have shown some variability, but the starting price of 70 euros is relatively low compared to previous hammer prices.

5. Sales expectations: Given that there are 2 auctions scheduled in the coming days, this may influence demand and, therefore, the hammer price.

Based on these factors, an estimated maximum purchase price for the coin with a grade of 80 (MS+) could be in the range of 120 to 150 euros. This is based on the analysis of previous hammer prices and the average hammer price, taking into account that interest in the coin may vary depending on demand at the auction.