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

1. Coin Condition: The coin has a condition rating of 70 (MS-), indicating that it is in acceptable condition but not of high quality. This generally affects the price, as coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for similar coins has been 84.45 euros.
- In previous auctions, coins with a similar condition (70) have reached hammer prices that varied, but some examples are:
- 55 euros (2020-05-26)
- 54 euros (2018-12-11)
- 44 euros (2018-07-04)
- 60 euros (2021-06-22)
- 85 euros (2022-10-18)

3. Starting Price: The starting price is 30 euros, which is relatively low compared to previous hammer prices.

4. Price Trends: Looking at the history, it seems that the hammer price can vary significantly depending on demand at the time of the auction. However, the range of hammer prices for coins in similar conditions suggests that the price could be in the range of 50 to 85 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 70 and 90 euros, considering that collector interest and demand at the time of the auction can influence the final price. Therefore, a reasonable maximum purchase price could be 85 euros.