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 relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 164.14 euros.
- The coin has been auctioned 38 times, of which it has sold 28 times, indicating good demand.
- Previous hammer prices varied significantly, with some reaching very high prices (for example, 600 euros in a previous auction).

3. Starting Price and Average Starting Price:
- The current starting price is 70 euros, which is relatively low compared to the average hammer price.
- The average starting price is 103.28 euros, suggesting that the current starting price could be attractive to buyers.

4. Recent Trends: In the most recent auctions, hammer prices have ranged from 55 to 100 euros for similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and that the price history shows that coins in similar conditions have reached higher prices in the past.

Therefore, a reasonable maximum purchase price could be 180 euros.