To estimate a maximum purchase price for the coin that is going to be auctioned, we can consider several factors, including the condition of the coin, the starting and hammer prices of previous auctions, and market behavior.

1. Condition of the coin: The coin in question has a condition rating of 95 (S/C-), which indicates that it is in very good condition. This generally translates to a higher price compared to coins with lower conditions.

2. Previous auction prices:
- The average hammer price for this coin in the past has been approximately 293.98 euros.
- In previous auctions, the hammer prices for coins with a similar condition (95) have varied, but some examples are:
- 400 euros (2020-11-24)
- 340 euros (2020-03-12)
- 320 euros (2019-12-11)
- 550 euros (2019-03-14)
- 460 euros (2019-01-24)

3. Current starting price: The starting price for the current auction is 450 euros. This suggests that the seller has expectations of a relatively high hammer price.

4. Market trends: Given that the coin has been auctioned 90 times and has had a sell-through rate of 95.56% (86 out of 90), this indicates a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 500 to 600 euros, considering that the starting price is 450 euros and that in the past, hammer prices exceeding 500 euros have been reached for coins in similar conditions.

Therefore, a reasonable maximum purchase price could be 550 euros.