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), which indicates that it is in fairly good shape, but not among the best qualities (FDC).

2. Auction History:
- The average hammer price for similar coins in the past is 153.72 euros.
- The condition of the coins auctioned in the past varies, but there are examples of coins with similar conditions that have sold for prices ranging from 60 to 900 euros, depending on quality and demand.

3. Starting and Hammer Price:
- The current starting price is 50 euros, which is relatively low compared to the average hammer price.
- In previous auctions, coins with similar conditions have had hammer prices that varied, but some recent examples show hammer prices of 90 euros (condition 70) and 95 euros (condition 75).

4. Recent Trends: In the most recent auctions, hammer prices for coins with conditions from 70 to 80 have been in the range of 90 to 160 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 90 to 150 euros. This is based on the historical hammer price for coins of similar condition and the average hammer price observed.

Therefore, a reasonable maximum purchase price could be 150 euros.