To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the starting price, auction history, and conditions.

1. Starting price: 75 euros.
2. Current condition: 75 (MBC).
3. Auction price history:
- In previous auctions with similar condition (75 MBC), the hammer prices have varied. For example:
- 90 euros (2020-07-02)
- 130 euros (2020-07-02, with estimated price of 150)
- 90 euros (2018-12-12)
- 220 euros (2013-12-04, with estimated price of 125)
4. Average hammer price: 103.61 euros.

Given that the condition of the coin is 75 (MBC), and considering that in the past hammer prices have reached up to 220 euros for coins in similar condition, we can establish a price range.

### Maximum purchase price estimation:
- Based on the average hammer price: 103.61 euros.
- Considering the highest price in history: 220 euros.

However, since the starting price is 75 euros and the average hammer price is lower than the historical maximum price, a reasonable estimated maximum purchase price could be slightly higher than the average hammer price, but not as high as the historical maximum.

### Estimated maximum purchase price:
150 euros.

This price reflects a balance between the average hammer price and the potential to reach higher prices in previous auctions, taking into account the current condition of the coin.