To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the conditions of the auctioned coins.

1. Starting and hammer price: The current starting price is 700 euros, and the average hammer price in previous auctions is 1135.53 euros. This suggests that, in general, coins of this reference tend to sell for a price higher than the starting price.

2. Auction history:
- In previous auctions, hammer prices have varied considerably, with some reaching up to 2600 euros (as in the March 2023 auction).
- The condition of the auctioned coins has influenced the hammer prices. Coins with higher conditions (such as 90 and 95) tend to achieve higher prices.

3. Current condition: In this case, there is no information about the condition of the coin to be auctioned. However, considering that previous conditions have ranged between 75 and 95, and that hammer prices have been high, we can assume that the coin could be in acceptable condition.

4. Maximum price estimation: Given that the average hammer price is 1135.53 euros and considering that some coins have reached significantly higher hammer prices, a reasonable maximum purchase price could be in the range of 1500 to 1800 euros, depending on the actual condition of the coin.

Therefore, an estimated maximum purchase price for this coin could be 1500 euros.