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

1. Current Condition: The coin has a condition of 75 (MBC), which indicates that it is in an acceptable state, but not of the highest quality.

2. Starting Price: The starting price is 80 euros, which sets a baseline for the auction.

3. Sales History:
- The average hammer price in previous auctions is 189.62 euros.
- Coins of similar condition (75) have been sold in the past at varying prices, with some examples being:
- 2011-05-27: 200 euros
- 2011-09-26: 200 euros
- 2013-09-18: 352.5 euros
- 2014-04-09: 140 euros
- 2015-03-13: 170 euros
- 2020-11-10: 500 euros (although this is an extreme case).

4. Recent Trends: In the most recent auctions, the hammer prices for coins of similar condition have ranged from 100 to 140 euros.

Based on this data, an estimated maximum purchase price could be between 150 and 200 euros, considering that the average hammer price is 189.62 euros and there are examples of previous sales exceeding 200 euros. However, since the condition is 75, it is wise not to exceed 200 euros to avoid overpaying relative to its state.

Therefore, a reasonable maximum purchase price could be 200 euros.