"UP" they go. #hodl.
Europeans buy and sell on cardmarket.com. There you can also see what cards were sold for. (And you can see what people ask for their cards in the respective languages and conditions). Don't forget to calculate the conversion from €>$. Another good tool is mtgstocks.com where you can also see the "market" price: what cards actually sell for. Compare the two tools, find a good middle ground. If not selling picemeal, you'll have to give generous discounts if yomeone is buying loads of cards. PM me for further conversation.