First off I know absolutely nothing about speakers/electronics so if any of this is useless info sorry.
I have a pioneer DEH-2000mp head which supposedly runs 50x4 watts running 2 Pioneer 6" x 9" 4-way Speakers TS-G971M in the rear deck and 2 Pioneer 4"x 6" 2-way Speakers, TS-G4642R in the front door. From what I understand I'm not getting 200 watts but more like 88 watts total. The volume is more than I need in fact I have yet to turn it up all the way, that said...I have my EQ set to +6 bass +1 mid and +2 treble and to get enough bass for my liking I have to turn it up too loud and it ends up distorting everything.
I've come to the conclusion that I need a sub to get the sound I'm looking for. The problem is I've spent ~200 dollars thus far and I'm looking for the cheapest way to get decent feeling and sounding bass. I would like to feel the bass in my seat when I drive even at low volumes if possible, I don't want to lose the little hearing I have left just to be able to feel my bass.
I did a little research and ended up finding a Pioneer amp thats 380 continuous watts after its bridged (Pioneer 2-Channel 380-Watt Amplifier GM-5300T $121.63) which I think should be more than enough but honestly I have no clue. beyond that I'm not sure if I would be better going with two 10", one 12" etc. It has a built in Adjustable low-pass crossover which Rest said was a good thing. I also found an alpine class D with 500 watts continuous but its $199.99.
Basically I would like some direction on what I should go after how much wattage I really need, if either of those will fulfill my needs.
As a side note the first sub recommended to me was a W7 the sub alone is out of my reasonable price range even if it is the coolest thing in the world sub wise.