I bought this Infinity Basslink 10" powered sub last year. I planned on putting it in my e30, but I ended up selling that car when I got my 135. My 135 has the premium sound so I have no need for this. I know a lot of guys on here, myself included, have a second car and that is what I'd imagine this would be a perfect upgrade for anyone who just wants to add a little bass to their system without spending very much. Bav auto still sells these for $350. It's still brand new in the box, never opened, still sealed from when I bought it. I think $150 is fair. I'd obviously prefer something local, but I will ship on your dime and its going to need a decent sized box.
Also open to trade...