Given that the coin has a conservation rating of 100 (S/C), indicating that it is in almost perfect condition, and considering that it is being auctioned for the first time, the starting price is set at 900 euros.

In this case, since there are no historical sales data for this coin, and the starting price is the same as the average starting price, it can be estimated that the interest in the coin could be high, especially due to its excellent condition.

Taking these factors into account, an estimated maximum purchase price could range between 1,200 and 1,500 euros, depending on the demand at the auction. This is based on the possibility that collectors may be willing to pay a premium for a coin in such good condition that has not been auctioned before.