To estimate a maximum purchase price for the coin that will be auctioned, we will consider several factors, including the starting price, the condition of the coin, and the hammer prices from previous auctions of coins with similar conditions.

### Relevant Data:
- Starting Price: 30 euros
- Condition of this coin: 85 (ebc-)
- Previous prices for this coin (similar condition):
- 2020-12-14: 20 euros starting price, 48 euros hammer price (condition 85)
- 2020-11-03: 25 euros starting price, 70 euros hammer price (condition 95)
- 2020-07-08: 25 euros starting price, 62 euros hammer price (condition 95)
- 2020-04-29: 75 euros starting price, 220 euros hammer price (condition not specified)
- 2019-10-22: 25 euros starting price, 60 euros hammer price (condition not specified)

### Analysis:
1. Starting Price: The starting price is 30 euros, indicating that the seller expects a minimum of 30 euros.
2. Previous Hammer Prices: The hammer prices for coins with a similar condition (85) have varied, but hammer prices of up to 70 euros can be observed for condition 85 and 62 euros for condition 95.
3. Price Trend: The hammer prices for coins in similar conditions have shown a range that can be considerably higher than the starting price.

### Estimation of Maximum Purchase Price:
Given that the highest hammer price for a similar condition has been 70 euros, and considering that the starting price is 30 euros, a reasonable maximum purchase price could be slightly higher than the highest observed hammer price.

Estimated Maximum Purchase Price: 70 - 80 euros.

This range allows for competitive bidding in the auction without exceeding the historical hammer prices for coins in similar conditions.