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

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

2. Auction History:
- The average hammer price from previous auctions is 1258.1 euros.
- Coins with similar condition (80) have been sold in the past, with hammer prices varying. For example, in 2021, a coin with a condition of 80 was sold for 1300 euros.
- The last auction in March 2023, with a condition of 95, reached a price of 2600 euros, indicating that the market is willing to pay more for coins in better condition.

3. Starting Price and Estimates:
- The current starting price is 1900 euros, which is higher than the historical average hammer price. This may indicate that the seller has high expectations, but it could also be an indicator of current demand.

4. Market Trends:
- Given that the coin has been auctioned 22 times and has had a sell-through rate of 95% (21 out of 22), this suggests there is consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 1500 and 2000 euros, considering that the starting price is 1900 euros and that the historical hammer price for similar conditions has been around 1300 to 1500 euros. However, if there is strong demand, it might be reasonable to consider a maximum of up to 2200 euros, but this will depend on the competition in the auction.

Therefore, an estimated maximum purchase price could be 2000 euros.