Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
What Nut Kracker said, plus if you're going to replace one, you'll (ideally) need to replace them all (they will get murdered to ensure your glass comes out in one piece). The updated upper and lower are a soft rubber, not hard plastic, so it's worth doing them all anyway.
Was the $150 for all the seals to be replaced or just the bottom ? Thx for the help