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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in an acceptable state, but not among the best qualities.

2. Auction History:
- The average hammer price in previous auctions is 782.62 euros.
- The average starting price is 455.06 euros.
- It has been auctioned 24 times, of which 19 have sold, indicating good demand.

3. Previous Prices:
- There are previous auctions with hammer prices that vary significantly, from 105 euros to 7250 euros, depending on the condition and other factors.
- In particular, it is noted that in auctions with similar conditions (75), the hammer prices have ranged from 202 to 736.92 euros.

4. Current Starting Price: The starting price is 100 euros, which is relatively low compared to the average hammer price.

Based on this data, an estimated maximum purchase price could be set in a range that considers the average hammer price and the current condition. Given that the condition is 75, a hammer price in the range of 300 to 500 euros seems reasonable, considering that there have been previous auctions in that range for similar conditions.

Therefore, an estimated maximum purchase price could be around 500 euros. This allows for a margin for competition in the auction and aligns with historical hammer prices for coins in similar conditions.