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

1. Current Condition: The coin has a condition of 90 (EF), indicating that it is in quite good shape.

2. Previous Auction Prices:
- In previous auctions, we have seen hammer prices that varied depending on the condition. For example:
- In 2024, a coin with a condition of 90 was auctioned for 220 euros.
- In 2022, a coin with a condition of 80 was auctioned for 190 euros.
- In 2019, a coin with a condition of 80 was auctioned for 120 euros.

3. Average Hammer Price: The average hammer price for this coin is 146.84 euros, which gives us an idea of what buyers are willing to pay.

4. Starting Price: The starting price is 120 euros, which is a good starting point.

Given that the condition of the coin is 90 and considering the previous auction prices, an estimated maximum purchase price could be in the range of 200 to 220 euros, based on the highest auction for a similar condition.

Therefore, an estimated maximum purchase price for this coin could be 220 euros.