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. Auction History:
- The average hammer price for similar coins has been 34.9 euros.
- In previous auctions, coins with a similar condition (80) have had hammer prices that varied, but some examples are:
- 4 euros (2020-07-02)
- 32 euros (2020-05-26)
- 25 euros (2019-04-24)
- 35 euros (2019-10-17)
- 50 euros (2020-02-12)
- The trend shows that the hammer price can vary significantly, but there are examples of sales exceeding 30 euros.

3. Starting Price and Average Starting Price:
- The starting price is 20 euros, and the average starting price is 23.59 euros. This suggests that the hammer price could be above these values.

4. Sales Expectations: Given that there are 2 auctions scheduled in the coming days, this could increase competition and, therefore, the hammer price.

5. General Trends: Historically, coins with a condition rating of 80 have had hammer price ranges that can reach up to 50 euros in some cases.

Based on these factors, an estimated maximum purchase price for this coin could be between 40 and 50 euros, considering that the condition is good and there is a price history that supports this estimate. However, it is important to be aware of the competition in the auction, as this can influence the final price.