Is the lettuce inside the wilted outer leaves still good?
Yes it is still good.

A lettuce that is kept outside (as in a farmer's market) will get wilted outer leaves, and the merchant will usually cut them off to make the heads nicer.

Depending on the resulting size; if they cut out too much compared to other lettuces, I might ask for a lower price if sold by the unit.

Personally, I will buy the lettuce with as much of the outer leaves as possible, even if I remove them at home, they will act as an outside protection against the elements.