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

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:
- The average hammer price for coins with similar conditions (around 70) has been approximately 270 to 300 euros in previous auctions.
- There are examples of coins with conditions of 70 that have sold for prices ranging from 200 to 480 euros, depending on demand and other factors.

3. Starting Price and Average Hammer Price:
- The current starting price is 250 euros, and the average hammer price in the past has been 435.18 euros. This suggests there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, hammer prices have been quite high, even reaching 1300 euros in some cases, although this may be related to higher conditions.

5. Demand and Supply: The coin has been auctioned 34 times in the past, with a sell-through rate of 97% (33 out of 34). This indicates there is consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 400 and 500 euros, considering that the condition is a limiting factor and that the average hammer price in the past has been 435.18 euros. However, if there is strong competition in the auction, the price could exceed this estimate.