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

1. Current Condition: The coin has a condition rating of 80 (MS+), 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 in previous auctions is 42.58 euros.
- The coin has been auctioned 44 times, of which it has sold 33 times, indicating good demand.
- In recent auctions, hammer prices have ranged from 35 to 70 euros, depending on the condition.

3. Starting Prices and Estimates:
- The current starting price is 30 euros, which is consistent with previous starting prices.
- Estimated prices in previous auctions have varied, but many have been in the range of 50 to 70 euros.

4. Recent Trends: In the most recent auctions, hammer prices have been in the range of 40 to 55 euros for coins with similar conditions.

Based on these factors, an estimated maximum purchase price for this coin could be between 55 and 70 euros, considering that the condition is good and there is a price trend in that range in recent auctions.

Therefore, a reasonable maximum purchase price could be 65 euros.