Where are you located? I'll assume the U.S., unless you say otherwise.
This is a chifferobe, not an armoire. A chifferobe combines into one unit a tall, narrow closet for hanging clothes and a tall, narrow chest of drawers. As you said, the exterior of yours is oak, with a cedar-lined interior for the closet side, from the early 20th century. The legs and skirting look like typical German construction, at least here in mid-Missouri, while the overall look is craftsman. You've got some condition issues, so I'd guess that the value is something like $150-$300, depending on where you are.
The best place to sell this would be an online venue like Craig's List, or a booth in an antique mall.