Based on the data provided, we can observe that the coin in question has had an average auction closing price of 154.84 euros in previous auctions. Additionally, the current condition of the coin is 90 (EBC).
Considering that the coin will be auctioned in the upcoming days with a starting price of 300 euros, we can estimate a maximum purchase price based on the historical average closing price and the current condition. Given the high condition (90 EBC), it is likely that the closing price will be in a similar range to the historical average price.
Therefore, an estimated maximum purchase price for this coin in the next auction could be around 150-200 euros, taking into account the condition and previous closing prices. It is important to note that in auctions, the final price can vary depending on demand and other factors, so it is advisable to pay attention to the auction to adjust the offer accordingly.