To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current starting price.

1. Current starting price: 1000 euros.
2. Average auction price in the past: 871.41 euros.
3. Previous auction prices:
- Auction prices have varied considerably, with some reaching up to 2600 euros in very good condition (condition value 110).
- Most auction prices are in a range of 400 to 1000 euros, with some exceptional cases.

4. Condition of the coin: There is no information about the condition of this coin, which makes the estimation more uncertain. However, based on the auction prices of similar coins, we can make an assumption.

5. Auction price analysis:
- Coins with a condition of 80 to 95 have had auction prices ranging from 600 to 1000 euros.
- Coins with a condition of 100 and 110 have reached significantly higher auction prices, but we do not have information about the condition of this coin.

Given that the starting price is 1000 euros and considering that the average auction price is 871.41 euros, an estimated maximum purchase price could be set in a range that reflects both the starting price and the potential auction price based on the condition.

Estimated maximum purchase price:
- A reasonable maximum price could be 1200 euros. This is based on the starting price and the potential that, if the coin has an acceptable condition, it could reach an auction price higher than the average.

Therefore, a maximum purchase price of 1200 euros seems to be a prudent estimate, taking into account historical data and the lack of information about the condition.