To estimate a maximum purchase price for the coin in question, we can analyze the provided data and consider several factors:

1. Current Condition: The coin has a condition of 80 (MBC+), indicating that it is in quite good shape. This suggests that its value should be in the upper range of coins with similar conditions.

2. Auction History:
- The average hammer price for coins of this reference is 533.13 euros.
- In previous auctions, hammer prices have varied, but there are several examples of coins with similar conditions (80-85) that have sold for prices ranging between 360 and 950 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 250 euros, which is below the average starting price of 357.14 euros. This could indicate that there is a buying opportunity at a lower price than average.

4. Sales Trends: The coin has been sold in 8 out of the 9 times it has been auctioned, indicating good demand.

5. Estimation Based on Previous Prices:
- The last auction with a hammer price of 500 euros and a condition of 80 suggests that this could be a good reference point.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 500-600 euros, as this price reflects both the current condition and the sales history of similar coins. However, since the starting price is 250 euros, it may be possible to acquire it for a price below this range, depending on the competition in the auction.