To estimate a maximum purchase price for the coin in question, we can analyze the provided data, taking into account the current condition of the coin (70, VF-) and the hammer prices from previous auctions.

1. Condition: The coin has a condition of 70, which is considered VF-. This suggests that its state is acceptable but not excellent. Generally, coins in better condition tend to reach higher prices.

2. Previous hammer prices: Looking at the hammer prices of coins with similar conditions:
- In 2020, a coin with a condition of 70 was auctioned for 110 euros.
- In 2013, a coin with a condition of 75 was auctioned for 462.4 euros.
- In 2019, a coin with a condition of 80 was auctioned for 340 euros.

3. Price trends: The average hammer price for previous auctions is 320.14 euros, indicating that, in general, coins of this reference tend to reach prices in that range.

4. Starting price: The current starting price is 300 euros, which is a good starting point. However, since the average hammer price is higher, it is reasonable to expect that the final hammer price will be higher.

5. Estimation: Considering all these factors, an estimated maximum purchase price could be in the range of 350 to 400 euros, taking into account that the condition is VF- and that there is a price history suggesting that coins in similar conditions have reached higher prices.

Therefore, an estimated maximum purchase price for this coin could be approximately 375 euros.

To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current starting price: 800 euros.
2. Condition of the coin: 85 (ebc-), indicating good condition, although not the best.
3. Auction history:
- It has been auctioned 5 times in the past, of which it has sold 3 times.
- The average starting price in previous auctions is 2045.3 euros, and the average hammer price is 3144.39 euros.
4. Previous prices:
- In 2012, it sold for 600 euros.
- In 2013, it sold for 6833.17 euros (condition 90).
- In 2013, it sold for 2000 euros (condition not specified).
- In 2015, a hammer price of 4334.7 euros was estimated (condition not specified).

Given that the current condition of the coin is 85, which is lower than 90 (which sold for 6833.17 euros), it is reasonable to expect that the hammer price will not reach that level. However, the average hammer price of 3144.39 euros suggests that there is significant potential for a higher selling price.

Taking all these factors into account, an estimated maximum purchase price could be in a range between the average hammer price and a bit more, considering the condition.

Therefore, an estimated maximum purchase price could be around 2500 to 3000 euros. This reflects a balance between the condition, the price history, and the current starting price.

To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Starting price: 300 euros.
2. Current condition: 75 (MBC), which is a fairly good condition, although not the best.
3. Auction history:
- In 2011, the coin was auctioned with an estimated price of 698.26 euros and sold for 1617.02 euros, with a condition of 90.
- In 2015, the starting price was 384.3 euros, with a final price of 720.55 euros, although the condition is not specified.

4. Average final price: 1168.79 euros, which is significantly higher than the current starting price.

Given that the current condition of the coin is 75, which is lower than the previous auction conditions (90), it is reasonable to adjust the estimated price downward compared to previous final prices.

### Estimation of the maximum purchase price:
- Considering the average final price of 1168.79 euros and adjusting for condition, we could estimate that the maximum purchase price could be in a range between 50% and 70% of that price, given that the condition is not the best.

- Calculation:
- 50% of 1168.79 euros = 584.39 euros
- 70% of 1168.79 euros = 818.15 euros

Therefore, a reasonable estimated maximum purchase price for this coin, considering its condition and auction history, could be between 584 and 818 euros.

To be more conservative, you might consider a maximum purchase price of 800 euros.