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

1. Current Condition: The coin has a condition rating of 70 (MS-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for coins of similar condition (70) in the past has been approximately 110 to 180 euros.
- In previous auctions, coins with a condition of 70 have sold for prices ranging from 110 to 180 euros.

3. Starting Price and Average Hammer Price:
- The current starting price is 100 euros, and the average hammer price in the past has been 172.8 euros. This suggests there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, hammer prices have shown an increase, especially for coins in good condition.

5. Demand and Supply: The coin has been auctioned 58 times, with a sell-through rate of 89.66% (52 out of 58). This indicates good demand.

Based on these factors, an estimated maximum purchase price for this coin could be between 180 and 220 euros, considering that the hammer price may be higher due to demand and condition. Therefore, a reasonable maximum purchase price could be 200 euros.