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

1. Current starting price: 200 euros.
2. Coin condition: 70 (MBC-), indicating good condition, although not the best.
3. Auction history:
- It has been auctioned 4 times in the past, of which it has sold 2 times.
- The average starting price in previous auctions is 126.25 euros, and the average hammer price is 92.5 euros.
- In previous auctions, the hammer prices have varied, but the highest was 135 euros in 2016.

4. Previous prices:
- In 2016, it was auctioned with a starting price of 120 euros and sold for 135 euros.
- In 2022, it was auctioned with a starting price of 150 euros, but it did not sell.

Given that the coin has a condition of 70 and considering the current starting price of 200 euros, which is significantly higher than previous hammer prices, it is likely that buyer interest may not justify such a high price.

Based on the price history and condition, an estimated maximum purchase price could be between the average hammer price (92.5 euros) and the highest previous hammer price (135 euros).

Therefore, a reasonable maximum purchase price could be around 150 euros. This reflects interest in the coin but also takes into account market realities and its condition.