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

1. Coin Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 113.18 euros.
- In recent auctions, hammer prices have varied, but there are examples of hammer prices exceeding 100 euros, even reaching up to 440 euros in a recent auction (although this may be an exceptional case).

3. Starting Price and Previous Prices:
- The current starting price is 75 euros, which is slightly higher than the average starting price of 64.73 euros.
- Previous hammer prices for coins with similar conditions have ranged from 75 to 135 euros.

4. Recent Trends: The price trend appears to be increasing, with recent auctions exceeding 100 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 120 to 150 euros. This is based on the auction price history and the condition of the coin, as well as the upward trend in auction prices.

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