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

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for this coin is 545.03 euros.
- In previous auctions, hammer prices have varied, but there are recent examples where the coin has reached hammer prices of up to 3200 euros (in the case of a condition rating of 85).
- The last auction with a similar condition (80) had a hammer price of 550 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 300 euros, which is slightly higher than the average starting price of 258.09 euros.

4. Sales Trends: The coin has been sold in 34 out of the 36 times it has been auctioned, indicating good demand.

5. Projections: Given that the coin has a condition rating of 80 and considering the price history, a hammer price around 550-600 euros seems reasonable, as it is consistent with the average hammer price and the behavior of previous auctions.

### Estimated Maximum Purchase Price
Taking all these factors into account, an estimated maximum purchase price for this coin could be between 600 and 700 euros. This would allow for competitive bidding in the auction without exceeding the historical hammer value for similar conditions.