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

1. Current Condition: The coin has a condition rating of 70 (MS-). This indicates that it is in an acceptable state, but not among the best qualities.

2. Starting Price and Previous Prices: The current starting price is 70 euros, and the average hammer price in previous auctions is 155.74 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 it has sold 36 times. This indicates high demand and good interest from collectors.

4. Previous Hammer Prices: Looking at previous hammer prices, we can see that they have varied considerably, but there are several examples where the hammer price has exceeded 100 euros, even reaching up to 400 euros in exceptional cases.

5. Recent Trends: In the most recent auctions, hammer prices have been in the range of 130 to 200 euros for coins of similar condition.

Based on these factors, an estimated maximum purchase price could be set in a range between 150 and 200 euros, considering that the interest in the coin is high and that the hammer price tends to be significantly higher than the starting price.

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