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 is an important factor, as coins in better condition tend to reach higher prices.

2. Previous Auction Prices: By observing the previous auction prices of coins with similar conditions (70-75), we can see that they have reached auction prices that vary, but are generally in the range of 60 to 160 euros. For example:
- In 2020, a coin with a condition of 70 was auctioned for 95 euros.
- In 2018, another coin with a condition of 70 was auctioned for 60 euros.

3. Average Auction Price: The average auction price for this coin is 158.53 euros, indicating that, in general, coins of this reference tend to reach higher prices.

4. Starting Price and Average Starting Price: The current starting price is 30 euros, and the average starting price is 70.72 euros. This suggests that the starting price is relatively low compared to the average auction price.

5. Recent Trends: In the most recent auctions, the auction prices have been quite high, which could indicate an upward trend in interest for this coin.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 150 to 200 euros, considering that the condition is good and there is growing interest in coins of this reference. However, since the starting price is 30 euros, it could be a good opportunity to acquire it at a lower price if the competition in the auction is not high.