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

1. Condition of the coin: The coin to be auctioned has a condition rating of 95 (EBC+), indicating that it is in very good shape. This is a positive factor that can increase its value.

2. Previous auction prices:
- The average hammer price for similar coins has been 296.25 euros.
- In previous auctions, hammer prices for coins with a similar condition (95) have varied, but there have been hammer prices of up to 300 euros.

3. Starting price: The starting price is 90 euros, which is relatively low compared to previous hammer prices.

4. Sales trends: The coin has been auctioned 9 times, of which it has sold 8 times. This indicates good demand and consistent interest in the coin.

5. Previous price estimates: Estimated prices in previous auctions for coins with a condition of 95 have been up to 150 euros, but hammer prices have reached significantly higher amounts.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 350 euros, considering that the average hammer price has been 296.25 euros and that there is potential for the hammer price to be higher due to the good condition and historical demand.

Therefore, a reasonable maximum purchase price could be 350 euros.