To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Current starting price: 1300 euros.
2. Current condition: 80 (MBC+), which is good condition, although lower than the 85 condition of the previous auction.
3. Average starting price in the past: 2123.84 euros.
4. Average hammer price in the past: 5322.18 euros.
5. Data from the previous auction: In 2014, the coin was auctioned with a starting price of 2947.67 euros and was hammered down at 5322.18 euros.

Given that the current condition is lower than that of the previous auction, it is reasonable to expect that the hammer price will not reach the same level as in 2014. However, the current starting price is significantly lower than both the average starting price and the hammer price of the previous auction.

Taking these factors into account, an estimated maximum purchase price could be positioned between the average hammer price of the previous auction and the current average hammer price, adjusted for condition.

We could estimate a maximum purchase price around 4000 euros, considering that condition is an important factor and that the starting price is relatively low. This allows for a margin for competition in the auction and the potential interest from other buyers.