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

1. Current Condition: The coin has a condition rating of 80 (MS+). This is an important factor, as coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for this coin in the past has been 252.42 euros.
- In previous auctions, coins with a similar condition (around 80) have had hammer prices that varied, but some examples are:
- 195 euros (2018-09-19)
- 240 euros (2019-04-24)
- 260 euros (2019-03-14)
- 250 euros (2020-03-12)

3. Starting Price and Estimated Price:
- The current starting price is 175 euros, and the estimated price is 300 euros. This suggests that there are expectations for the coin to sell at a higher price.

4. Recent Trends: In the most recent auctions, the hammer price has been in a range that suggests the coin could reach higher prices, especially if there is interest in the auction.

Based on these factors, a reasonable maximum purchase price could be in the range of 250 to 300 euros, considering that the average hammer price has been 252.42 euros and that the condition of the coin is good.

Therefore, an estimated maximum purchase price could be approximately 300 euros.