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

1. Current Condition: The coin has a condition rating of 95 (EF+), indicating that it is in very good shape. This generally translates to a higher price compared to coins in lower condition.

2. Average Hammer Price: The average hammer price for this coin is 880.71 euros. This is an important indicator of the value that collectors are willing to pay.

3. Auction History: The coin has been auctioned 45 times, of which it has sold 28 times. This suggests that there is consistent interest in the coin, which may increase its value.

4. Previous Prices: Looking at previous hammer prices, there are several examples of prices exceeding 100 euros, with some reaching much higher figures (for example, 22,000 euros in a recent auction). However, these extreme prices may be exceptional and not necessarily representative of the overall value.

5. Starting Price: The current starting price is 90 euros, which may be a good starting point for the auction.

Given all this, an estimated maximum purchase price could be in a range that considers the average hammer price and the condition of the coin.

Estimated Maximum Purchase Price:

We could consider a maximum purchase price around 1,000 euros, as it is above the average hammer price and reflects the good condition of the coin. However, it is important to keep in mind that the final price will depend on the competition in the auction and the interest of collectors at that time.