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 70 (VF-), which indicates that it is in an acceptable state, but not among the best qualities. This can influence the price, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for coins of this reference is 236.91 euros.
- In previous auctions, hammer prices have varied, with some reaching up to 500 euros, but there are also cases where the price was significantly lower.
- The last auction with a similar condition (70) had a hammer price of 500 euros.

3. Starting Price: The starting price of 300 euros is a good indicator of what is expected to be obtained for the coin, but it does not necessarily reflect the final hammer price.

4. Sales Trends: The coin has been sold in 11 out of 13 auctions, indicating reasonable demand.

Based on these factors, an estimated maximum purchase price could be situated in a range between the average hammer price (236.91 euros) and the highest price reached in previous auctions (500 euros). Given that the condition is 70, a reasonable maximum purchase price could be:

Estimated maximum purchase price: 400 euros.

This price reflects a balance between the current condition, the price history, and the demand observed in previous auctions.