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

1. Condition of the coin: The coin in question 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 with lower conditions.

2. Starting price and previous prices: The current starting price is 375 euros. In previous auctions, coins with a similar condition (95) have reached hammer prices that varied, but some have exceeded 350 euros. For example, in the auction on 2020-12-15, a coin with a condition of 95 was sold for 350 euros.

3. Price trends: Looking at the hammer prices of similar coins in the past, it seems that the range of hammer prices for coins in condition 95 has been between 350 and 420 euros in recent auctions.

4. Auction expectations: Given that there are 3 auctions scheduled in the coming days, this could increase competition and, therefore, the hammer price.

Based on these factors, an estimated maximum purchase price could be in the range of 400 to 450 euros, considering that the coin is in excellent condition and there is market interest. However, given the starting price of 375 euros, a hammer price of up to 420 euros seems reasonable and achievable.

Therefore, an estimated maximum purchase price could be 420 euros.