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

1. Current Condition: The coin has a condition of 30 (BC+), which indicates that it is not in very good shape. This generally reduces its value compared to coins in better condition.

2. Auction History: By observing the hammer prices of coins with similar conditions in the past, we can see that prices have varied. For example, in previous auctions, coins with conditions ranging from 30 to 70 have had hammer prices ranging from 100 to 185 euros.

3. Starting Price and Average Hammer Price: The current starting price is 110 euros, and the average hammer price for this coin in the past has been 132.77 euros. This suggests that the hammer price could be in a similar range.

4. Recent Trends: In the most recent auctions, hammer prices have shown some variability, but generally, coins with similar conditions have reached hammer prices around 140-160 euros.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 150-160 euros. This is based on the analysis of previous auctions and the current condition of the coin.