To estimate a maximum purchase price for the coin that is going to be auctioned, we can analyze the provided data. Here are some key points to consider:

1. Starting price: 225 euros.
2. Auction history: The coin has been auctioned 1,295 times, of which it has sold 998 times. This indicates good demand.
3. Average hammer price: 98.9 euros, suggesting that, in general, coins of this reference sell for a significantly lower price than the current starting price.
4. Previous prices: There are several hammer prices in the past that varied considerably, with some reaching up to 360 euros in higher conservation conditions.

Since there is no information about the condition of the current coin, it is difficult to make an accurate estimate. However, considering the starting price and the history of hammer prices, a reasonable maximum purchase price could be slightly higher than the average hammer price, but not as high as the starting price.

Estimated maximum purchase price: 150 euros.

This price reflects a balance between historical demand and the starting price, taking into account that the condition of the coin is unknown.