To estimate a maximum purchase price for the coin that will be auctioned, we can consider several factors based on the provided data:

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

2. Previous auction prices:
- The average hammer price for similar coins has been 281.39 euros.
- In previous auctions, coins with a condition rating of 95 have reached hammer prices that varied, but some examples are:
- 305 euros (2020-12-15)
- 400 euros (2020-07-02)
- 270 euros (2018-12-11)
- 320 euros (2023-03-16)

3. Starting price: The starting price for the current auction is 250 euros, which is a reasonable starting point.

4. Price trends: Observing the trends, it seems that coins with a similar condition have often had hammer prices that exceed the starting price, especially in high condition.

Based on these factors, an estimated maximum purchase price could be in the range of 350 to 400 euros, considering that the highest hammer price in previous auctions for coins of similar condition has been 400 euros. This also takes into account the possibility that bidders may be willing to pay a bit more for a coin in such good condition.

Therefore, an estimated maximum purchase price could be approximately 400 euros.