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

1. Current Condition: The coin has a condition of 70 (VF-). This indicates that it is in an acceptable state, but not among the best qualities.

2. Starting Price: The starting price is 90 euros. This is the starting point for the auction.

3. Sales History:
- The average hammer price for similar coins is 141.24 euros.
- In previous auctions, coins with similar conditions (70) have had hammer prices that varied, but some examples are:
- 75 euros (2020-11-10)
- 130 euros (2020-12-15)
- 110 euros (2020-11-10)
- 150 euros (2020-10-21)
- 130 euros (2020-09-22)

4. Recent Trends: In recent auctions, the hammer price has shown a range that can reach up to 360 euros for coins in better condition, but for the current condition, it is more reasonable to expect a lower price.

5. Auction Expectations: Given that there is a scheduled auction and interest in the coin may vary, it is important to consider that the price may fluctuate depending on demand.

Based on these factors, an estimated maximum purchase price for this coin could be between 130 and 150 euros, considering that it is a reasonable price based on its condition and sales history. However, if there is significant interest in the auction, it could reach a bit higher, but it is wise not to exceed 150 euros to avoid overpaying.