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

1. Current starting price: 150 euros.
2. Coin condition: 75 (MS), which is a fairly good condition.
3. Auction history:
- The average hammer price in previous auctions is 182.5 euros.
- The coin has been auctioned 15 times, of which it has sold 14 times, indicating good demand.
- In previous auctions with similar condition (75), hammer prices have varied, but there are examples of sales reaching up to 320 euros.

4. Previous hammer prices:
- In 2023, a coin with condition 75 sold for 320 euros.
- In 2022, it sold for 300 euros.
- In 2019, the hammer price was 170 euros.

Given that the coin's condition is good and there are examples of high hammer prices in the past, we can consider that the hammer price could be in a high range.

### Estimation of the maximum purchase price:
- Based on the average hammer price (182.5 euros) and the higher hammer prices (up to 320 euros), a reasonable maximum purchase price could be between 200 and 250 euros, considering that the starting price is 150 euros and that there is a good possibility that the hammer price will exceed the starting price.

Therefore, an estimated maximum purchase price could be 250 euros.