I've never sold any lego before. Just made my first sale on a complex piece in the 8-14 yr old range. We made it up, and photographed it made, just to be sure that all the bits were there. It has hundreds of bits & I got a good price for it. I'm selling it with packaging & full instructions.
I've been told that there are often disputes about lego arriving without all the pieces. To avoid any issues with this, it is best to send the items in their made state.
I've just sent a message to the buyer to say that I intend to send the lego in its made state. I'm not being a nutter am I?