To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins in the past is 165.8 euros.
- The coin has been auctioned 19 times, of which it has sold 16 times, indicating good demand.
- Previous hammer prices for coins with a similar condition (80) have varied, but there are examples where they have sold for 80, 135, and 65 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 30 euros, which is relatively low compared to the average starting price of 83.72 euros.

4. Price Trends:
- In recent auctions, the hammer price has ranged from 46 to 80 euros for coins with similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 80 to 120 euros, considering that the condition is good and that the price history shows that similar coins have reached higher prices in the past.

Therefore, a reasonable estimated maximum purchase price could be 100 euros.