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

1. Condition: The coin has a condition of 70 (MBC-), which indicates that it is in an acceptable state, but not of the best quality. This influences the price, as coins in better condition tend to fetch higher prices.

2. Auction history:
- It has been auctioned 6 times, of which it has sold 4 times. This indicates that there is interest in the coin.
- The average starting price in previous auctions is 157 euros, and the average hammer price is 156.25 euros. This suggests that, in general, coins of this reference tend to sell close to their starting price.

3. Previous prices:
- In 2016, the coin sold for 260 euros with a starting price of 150 euros, indicating that there may be potential for price increase depending on demand.
- In 2022, the starting price was 125 euros and although it did not sell, the estimated price was 160 euros, showing that interest can fluctuate.

4. Current starting price: The current starting price is 250 euros, which is significantly higher than the average starting price of previous auctions. This may indicate that the seller expects an increase in interest or in the value of the coin.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 200 to 250 euros. This is based on the price history, the condition of the coin, and the current starting price. However, since the starting price is 250 euros, it may be wise not to exceed this amount unless there is strong competition in the auction.

Therefore, a reasonable maximum purchase price could be 240 euros. This allows for a margin for competition without exceeding the starting price.