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 for similar coins in the past has been 136.13 euros.
- In previous auctions, we have seen hammer prices that varied, but some relevant examples are:
- In 2023, a coin with a condition rating of 85 was sold for 220 euros.
- In 2022, a coin with a condition rating of 85 was sold for 130 euros.
- In 2021, a coin with a condition rating of 80 was sold for 90 euros.

3. Starting Price and Estimated Price:
- The current starting price is 80 euros, and the estimated price is 100 euros. This suggests that the seller expects moderate interest in the coin.

4. Sales Trends: The coin has been sold in 39 out of the last 45 auctions, indicating good demand.

Based on these factors, a reasonable maximum purchase price could be in the range of 150 to 180 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, an estimated maximum purchase price could be 150 euros.