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

1. Current starting price: 475 euros.
2. Current condition: 80 (MBC+), which is quite a good condition.
3. Auction history:
- In November 2022, the coin was auctioned with a starting price of 250 euros and an estimated price of 325 euros, but it did not sell.
- In September 2024, it will be auctioned with a starting price of 400 euros and an estimated price of 600 euros, with a condition of 95 (very good).

4. Average starting price: 375 euros, indicating that the current starting price (475 euros) is above the historical average.

5. Times sold: It has only been sold once in the past, which may indicate that there is less demand or interest in this particular coin.

Given that the current condition is good (80) and considering the starting price and auction history, an estimated maximum purchase price could be positioned between the current starting price and the estimated price of the next auction.

Taking all these factors into account, a reasonable maximum purchase price could be around 500 to 550 euros. This allows for some competition in the auction, but also considers that interest may not be very high given the sales history.