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 of 70 (MS-). This indicates that it is in an acceptable state, but it is not of the highest quality.

2. Previous Auction Prices: By observing previous auction prices for coins with similar conditions, we can see that:
- In past auctions, coins with conditions ranging from 70 to 80 have reached hammer prices between 60 and 100 euros.
- For example, in the auction on 2020-07-08, a coin with a condition of 75 was sold for 64 euros, and in the auction on 2022-04-27, a coin with a condition of 30 was sold for 70 euros.

3. Average Hammer Price: The average hammer price for this coin is 103.87 euros, suggesting that, in general, coins of this reference tend to sell for higher prices.

4. Starting Price: The starting price is 30 euros, which is relatively low compared to previous hammer prices.

5. Sales Trends: The coin has been auctioned 47 times, of which 40 have resulted in sales. This indicates good demand and consistent interest in this reference.

Based on these factors, an estimated maximum purchase price for the coin with a condition of 70 could be in the range of 80 to 100 euros, considering that the average hammer price is 103.87 euros and that condition is an important factor in determining price.

Therefore, a reasonable maximum purchase price could be 90 euros.