That’s correct. Selling wormholes can be lucrative, however it isn’t so common you would find a wormhole for sale which still has another corporations assets (such as citadels) in. Therefore, finding an empty wormhole, without inhabitants, and the other aspects a buyer is looking for such as planets, moons, and the static can be few and far between.
I have lived in many wormholes myself, only ever “purchased” a wormhole once. The rest I’ve found with a few hours of exploring.