To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Condition: The coin has a condition of 80 (MS+), which is higher than the previously auctioned coins that have a condition of 75. This suggests that the coin could have a higher value than the previous ones.

2. Previous auction prices: The previous auction prices for coins with a condition of 75 have been 240, 310, 250, and 310 euros. The average auction price for these coins is approximately 277.5 euros.

3. Starting price and average auction price: The current starting price is 200 euros, and the average auction price is 277.5 euros. This indicates that the auction price could be in a similar or higher range than the average price, especially considering the better condition of the current coin.

4. Demand and supply: Since there are no auctions scheduled in the coming days, this could increase demand and interest in the coin, potentially leading to a higher auction price.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 300 to 350 euros, given that the condition is better than the previously auctioned coins and interest in the coin could be high. However, it is important to remember that the final price will depend on the competition in the auction and the willingness of bidders to pay.