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

1. Starting Price: 70 euros.
2. Condition: The coin has a condition rating of 75 (MBC), indicating that it is in fairly good shape.
3. Auction History:
- It has been auctioned 5 times in the past, of which it has sold 4 times.
- The average hammer price in previous auctions is 108.75 euros.
- In the most recent auction (2023-12-18), the coin was hammered at 40 euros, but in a previous auction (2020-04-29), it was hammered at 250 euros, indicating variability in prices depending on demand and condition.

4. Average Starting and Hammer Price: The average starting price is 50 euros, but the average hammer price is significantly higher (108.75 euros), suggesting that buyers are willing to pay more than the starting price.

Given that the condition of the coin is good (75) and considering the hammer price history, an estimated maximum purchase price could be positioned in a range between the average hammer price and a bit more, given that the coin has a starting price of 70 euros.

Estimated Maximum Purchase Price: It could be reasonable to estimate a maximum purchase price of around 150-200 euros, taking into account the hammer price history and the condition of the coin. This would allow for competitive bidding in the auction without exceeding the market value observed in previous auctions.

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

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

2. Auction History:
- The average hammer price for similar coins has been 245.43 euros.
- In previous auctions, we have seen hammer prices that varied significantly, ranging from 50 euros to 1200 euros, depending on the condition and other factors.

3. Starting Price: The starting price is 80 euros, which may be a good indicator of the seller's expectations.

4. Price Trends: In recent auctions, coins with similar conditions have reached hammer prices ranging between 100 and 290 euros.

5. Analysis of Previous Prices:
- In auctions with conditions of 75, hammer prices have been around 60 to 360 euros.
- The most recent auction with a condition of 75 had a hammer price of 360 euros.

Based on this data, an estimated maximum purchase price for this coin could be in the range of 200 to 300 euros, considering that the condition is an important factor and that the average hammer price is significantly higher than the starting price.

Therefore, a reasonable maximum purchase price could be 250 euros.

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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for coins with a similar condition (75) in the past has been approximately 60-70 euros.
- In previous auctions, coins with a condition of 75 have reached hammer prices of up to 110 euros, as seen in the auction on 2023-02-16.

3. Starting Price and Average Starting Price: The current starting price is 35 euros, which is below the average starting price of 53.39 euros. This suggests that there is potential for the hammer price to be higher.

4. Recent Trends: In the most recent auctions, the hammer price has shown a trend of being higher, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 80 and 110 euros, considering that the condition is favorable and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 100 euros.