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

1. Current Condition: The coin has a condition of 30 (BC+), indicating that it is in relatively low condition. This may negatively affect its value compared to coins in better condition.

2. Auction History:
- The coin has been auctioned 7 times and has sold on all occasions, indicating consistent interest in the coin.
- The average hammer price in previous auctions is 186.57 euros.
- In the most recent auction (2022), a coin with the same condition (30) was hammered at 151 euros.

3. Previous Hammer Prices:
- In 2021, a coin with a condition of 90 sold for 480 euros, and another with a condition of 50 sold for 170 euros. This shows that the price can vary significantly with condition.
- In 2014 and 2017, the hammer prices for coins with similar conditions (30 and 50) ranged from 110 to 150 euros.

4. Price Trends: The average starting price has been 113 euros, and the average hammer price has been 186.57 euros. However, given that the condition of the coin in question is 30, it is likely that the hammer price will fall within the lower range of these values.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 120 and 150 euros, considering that the condition is a limiting factor. A price of 130 euros could be a reasonable starting point for an offer.