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+), indicating that it is in relatively good shape. This suggests that its value could be in the upper range of coins with similar conditions.

2. Auction History:
- The average hammer price for coins with similar conditions (80) has been 65 euros in a previous auction (2022-06-01).
- In other auctions with a condition of 80, hammer prices have varied, but they have generally remained in a range of 15 to 80 euros.

3. Starting Price and Average Hammer Price:
- The current starting price is 15 euros, which is quite low compared to the average hammer price of 48.8 euros.
- The average starting price of 32.27 euros also suggests that there is potential for an increase in the hammer price.

4. Sales Trends: The coin has been sold on all previous occasions, indicating consistent demand.

Based on these factors, an estimated maximum purchase price could be in the range of 60 to 80 euros, given that the condition is good and the hammer price history for similar coins supports this estimate.

Therefore, a reasonable maximum purchase price could be 70 euros.