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 80 (MS+), indicating that it is in quite good shape. This is important because coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for this coin has been 188.08 euros.
- In previous auctions, hammer prices for coins with a similar condition (80) have varied, but there are examples where they have sold for prices close to 200 euros or more.
- For instance, in the auction on January 31, 2023, a coin with a condition of 80 was hammered down at 240 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 100 euros, which is relatively low compared to the average hammer price.
- The average starting price has been 113 euros, suggesting that the current starting price is competitive.

4. Market Trends: Given that the coin has been auctioned 54 times and has a sell-through rate of 90.74% (49 out of 54), this indicates consistent demand.

Based on these factors, an estimated maximum purchase price could be between 220 and 250 euros, considering that the condition is good and there are precedents for sales in that range. This also takes into account the possibility that some bidders may be willing to pay more for a coin in good condition.