Sorry, the other interpretation allows for a munchkin to get an "extra" move out of a big item.
- Play all of your movement tokens (they're now all red).
- Play a second Big item.
- Remove one of your movement tokens (a red one, since that's all you have).
- Sell the Big item.
- Get a new move token (comes in "as if it were the beginning of the turn", ie, green).
- Use your green movement token to make another move.
- Repeat if possible.