Yes, this can be set up in the shipping tab of eCart.
You can use the triggers:
Subtotal For Entire Cart Contents:
If the subtotal price for the cart is ">" a value of "0"
AND
Subtotal For Entire Cart Contents:
If the subtotal price for the cart is "<" a value of "50"
this would trigger the rule if the cart subtotal is less than $50 offering free shipping after that amount