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

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

2. Auction History:
- The average hammer price for similar coins has been 133.95 euros.
- In previous auctions, coins with a similar condition (around 70) have had hammer prices that varied, but some examples are:
- 120 euros (2020-12-15)
- 140 euros (2020-11-19)
- 130 euros (2019-05-23)
- The trend shows that coins with a condition of 70 have reached hammer prices in the range of 100 to 140 euros.

3. Starting Price and Estimated Price:
- The starting price is 90 euros, and the estimated price is 150 euros. This suggests that there are expectations for the coin to sell for a higher price than the starting price.

4. Demand and Auction Frequency:
- The coin has been auctioned 189 times, with a sell-through rate of 94.7%. This indicates good demand and consistent interest in the coin.

Based on these factors, an estimated maximum purchase price could be in the range of 130 to 150 euros, considering that the average hammer price for coins in similar conditions has been approximately 133.95 euros.

Therefore, a reasonable maximum purchase price could be 150 euros.