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 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Starting Price and Average Hammer Price: The starting price is 70 euros, and the average hammer price in previous auctions is 142.39 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Sales History: The coin has been auctioned 38 times, of which 36 have been sold. This indicates high demand and good interest in the coin.

4. Previous Prices: Looking at previous hammer prices for coins with a similar condition (70), we can see that they have reached hammer prices of up to 550 euros in the case of a condition of 95, and lower prices in conditions of 70 and 80, which range between 130 and 250 euros.

5. Recent Trends: In the most recent auctions, the hammer prices have been 250 euros and 280 euros for conditions of 75 and 80, suggesting that interest and prices are on the rise.

Based on these factors, an estimated maximum purchase price for the coin with a condition of 70 could be in the range of 200 to 250 euros, considering that the average hammer price is 142.39 euros and that there is potential for an increase based on demand and interest in the coin.

Therefore, a reasonable maximum purchase price could be 250 euros.