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

1. Current Condition: The coin is in a condition of 90 (EF), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins in lower conditions.

2. Auction History:
- The average hammer price for similar coins in the past has been 146.84 euros.
- In previous auctions, coins with similar conditions (around 80-90) have reached hammer prices that varied, but some examples are:
- 190 euros in a recent auction (2024-09-18) with a condition of 90.
- 130 euros in an auction with a condition of 80 (2022-10-19).
- 220 euros in an auction with unspecified condition (2018-05-10).

3. Starting Price and Estimates:
- The current starting price is 120 euros, which is reasonable given the history of starting and hammer prices.
- The estimated price for the current auction is 250 euros, suggesting that there are expectations for the coin to reach a higher price.

4. Market Trends: Given that the coin has a history of successful sales and the condition is good, it is likely that collector interest and the market in general will keep prices in a high range.

Based on these factors, an estimated maximum purchase price could be around 200-250 euros, considering that the hammer prices in previous auctions have reached similar figures and that the condition of the coin is favorable. However, it is important to keep in mind that the final price may vary depending on the competition in the auction and the interest of collectors at that time.