Based on the data provided, we can observe that the coin in question has had an average starting price of 28.63 euros in previous auctions, with an average closing price of 45.75 euros. The current condition of the coin is 30 (BC+).

Some previous prices of this coin in past auctions have been as follows:

- In an auction on September 17, 2020, the coin had a starting price of 18 euros, an estimated price of 30 euros, and a closing price of 45 euros, with a condition of 70.
- In an auction on April 23, 2015, the coin had a starting price of 75 euros, an estimated price of 125 euros, and a closing price of 85 euros.
- In an auction on February 5, 2015, the coin had a starting price of 15 euros, an estimated price of 25 euros, and a closing price of 17 euros.
- In an auction on September 24, 2019, the coin had a starting price of 30 euros, an estimated price of 50 euros, and a closing price of 48 euros.
- In an auction on October 15, 2018, the coin had a starting price of 40 euros and a closing price of 46 euros.
- In an auction on April 28, 2022, the coin had a starting price of 18 euros, an estimated price of 30 euros, and a closing price of 55 euros.
- In an auction on April 24, 2024, the coin had a starting price of 18 euros and a closing price of 45 euros.

Given that the coin is in a condition of 30 (BC+), and considering the previous closing prices, as well as the average starting price and estimated price in previous auctions, we could estimate a maximum purchase price for this coin at around 50-55 euros. It is important to note that the final price may vary depending on the demand at the auction and other factors that may influence the valuation of the coin.