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

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

2. Current Starting Price and Previous Prices: The current starting price is 120 euros. In previous auctions, the average hammer price has been 193.08 euros, indicating that coins of this reference usually sell for above their starting price.

3. Sales History: The coin has been auctioned 13 times and all have been sold, suggesting a consistent demand. Additionally, the highest recorded hammer price was 550 euros in 2015, indicating potential for high prices in the future.

4. Recent Trends: In the most recent auctions, hammer prices have been quite high, especially in 2023, where it sold for 320 euros with a condition rating of 90.

5. Comparison with Similar Conditions: In the 2022 auction, a coin with a condition rating of 70 sold for 110 euros, which can serve as a reference for the hammer price of the current coin.

Taking all these factors into account, an estimated maximum purchase price for the coin with a condition rating of 70 could be in the range of 200 to 250 euros, considering that the average hammer price is 193.08 euros and that there is potential to reach higher prices depending on demand and condition.

Therefore, a reasonable maximum purchase price could be 250 euros.