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

1. Condition of the coin: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Current listing price and previous prices: The current listing price is 450 euros. In previous auctions, we have seen hammer prices that vary significantly, but there are examples of coins with similar conditions that have sold for higher prices. For instance, in 2019, a coin with a condition of 95 sold for 600 euros.

3. Price trends: The average hammer price for similar coins is 128.81 euros, but this may be influenced by coins of lower condition. Given that this coin has a high condition rating, it is reasonable to expect its hammer price to be above this average.

4. Sales history: The coin has been auctioned 40 times, of which 37 have sold. This indicates good demand and a history of successful sales.

5. Recent hammer prices: In the most recent auctions, the hammer prices have been 120 euros and 142 euros for coins of similar condition.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 600 to 700 euros, given its condition and the history of hammer prices in previous auctions. However, since the listing price is 450 euros, it is possible that buyers may be willing to pay a bit more, but not necessarily reaching the estimated maximum. A realistic hammer price could be around 500-600 euros.