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 (MS-), which indicates that it is in an acceptable state, but not among the best qualities. This can influence the price, as coins in better condition tend to reach higher prices.

2. Auction history:
- The average hammer price for coins of the same reference is 333.33 euros.
- In previous auctions, hammer prices have varied, but there are examples of coins with similar condition (70) that have sold for prices between 170 and 290 euros.

3. Starting price: The starting price for this auction is 180 euros, which is a reasonable starting point.

4. Price trends: Observing previous hammer prices, it seems that coins with a condition of 70 have had a hammer price range from 170 to 290 euros. However, there is one case where a coin with a condition of 95 sold for 1200 euros, indicating that there is a market for higher prices, but that does not directly apply to this coin.

5. Estimation: Given that the average hammer price is 333.33 euros and considering the condition of the coin, an estimated maximum purchase price could be set in a more conservative range.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 250-300 euros. This is based on the hammer price history and the current condition of the coin.