My dad originally bought these for a 1969 corvette he is having restored. He decided to go a different route and is having me sell them for him. They are new in box. According to the forums these are perfect for BMWs and will fit under the seats, giving you extra quality sound and bass.
My dad wants to sell them for no less than $200 or $250 shipped anywhere.
He also purchased a used AMP for them which is also for sale, I can't guarantee it as I'm not an audio guy, but I see no reason why this wouldnt work in a BMW. Its a GS-4300S Redline AMP 100w x 4 Channel. He said he'll sell this for $75.
Pictures of everything are attached. PM me.