To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the condition of the auctioned coins.

1. Current starting price: 1000 euros.
2. Average hammer price in the past: 1448.25 euros.
3. Auction history:
- The coin has been auctioned 9 times and has sold on all occasions.
- Previous hammer prices varied, but there are some relevant data:
- In 2018, a coin with a condition of 70 was hammered at 700 euros.
- In 2018, another coin with a condition of 80 was also hammered at 700 euros.
- In 2015, a coin with a starting price of 1800 euros was hammered at 2000 euros (no condition information available).
- In 2022, a coin with a condition of 30 was hammered at 260 euros.

4. Condition: There is no information about the condition of the current coin, which complicates the estimation a bit. However, we can observe that coins with conditions of 70 and 80 sold for 700 euros, and those with a condition of 30 sold for 260 euros.

5. Estimation: Given that the average hammer price is 1448.25 euros and considering that the starting price is 1000 euros, a reasonable maximum purchase price could be in a range above the starting price, but not as high as the average hammer price, given the lack of information about the condition.

Taking all these factors into account, an estimated maximum purchase price could be around 1200 to 1300 euros. This is based on the fact that the starting price is 1000 euros and the average hammer price is significantly higher, but also considering the lack of information about the current condition.