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

1. Starting price: 70 euros.
2. Current grade: 70 (MBC-).
3. Auction history: The coin has been auctioned 12 times and has sold in all of them, indicating good demand.
4. Average hammer price: 119.17 euros, suggesting that, on average, coins of this reference sell for a price higher than the starting price.
5. Previous prices:
- In recent auctions, hammer prices have varied, but there are examples where hammer prices have reached up to 270 euros (although with a higher grade).
- The last auction with a grade of 80 had a hammer price of 190 euros.

Given that the grade of the coin in question is 70 (MBC-), which is lower than the grades of some coins that have sold for higher prices, but still an acceptable grade, we can make an estimation.

### Estimation of the maximum purchase price:
- Considering the average hammer price (119.17 euros) and the fact that grade is an important factor, a reasonable maximum purchase price could be in the range of 120 to 150 euros. This is based on the fact that the coin has a history of successful sales and a hammer price that exceeds the starting price.

Therefore, an estimated maximum purchase price could be 150 euros.