For the front I have some 5 1/4 Pioneers. In the sound bar I have 6 1/2 $25 cheapies from Wally World.
For the back I bought a cheap brand box at Wally World last year.
I have no amp just a 50 x 4 cd player but itall really sounds great
I then cut a thick piece of wood and bolted the box to it pointing downward
Facing downwards, the bass is nice.
I put some brackets on each side and used wing nuts to secure it. Then I rattlecan bedlined it all.