I did post this as a sub system for around the $400 price range to help the OP with his listed budget.

Audiopipe Adsm1300 (amp) apx $115
4 guage wire kit (a real one not fake from ebay) $50
a single prefab sealed box from Sonic Electronics (do not buy a pre fab ported box as they are always tuned way too high) $80
a dual 2 Ohm 12" Skar sub $179

$424 Total


those little Audiopipe amps are about the best bang for the buck amps out but need a 1 ohm load that is why I recommended the dual 2 ohm Skar Sub.

The Skar sub really does perform quite well and can be reconed for $40 with a kit from Skar.


My system is over the top a bit and not needed at all.
I built it (a bit off the subject but...) as I had built a SQ type system for the Honda (which my girlfriend drives 60 miles a day to work)

I setup a JL 10w3 in a sealed box with a baffle board that sealed it from the trunk.
I used a smaller 200 watt sub amp

The car sounded good (also has a high quality head unit and front stage.)
But her complaint was constantly the car did not have enough Bass.
After listening to the almost weekly complaints about the amount of Bass for around 6 months, I said fine, "you want Bass, I'll give you some Bass then!" And I built the system that showed a picture of above.

She does not complain about the amount of Bass anymore

Can the OP get a sub stage for $400, well I guess it all depends on how much bass is acceptable to him.

The trunk on these Honda's are hard to get good Bass out of. Most of my systems have been in SUV's or Trucks - much easier to work with.

 

never had a problem getting bass out of my trunk. just sayin. if you are haveing trouble getting bass I would suggest from looking at your picture investing in some sound dampener.

 

The passenger compartment has around 1/2 of a roll of Fat Mat in it.
I installed the current sub system in November and it was too cool to install more deadening (IMO) as you can see I pulled all the trunk panels and it will be getting fully deadened this Spring.

When I talked about the trunk sucking up a lot of Bass, I say that because the same JL / MB Quart Amp / Sealed box was in the back of a Ford Edge (medium-ish sized SUV) and had way more Bass than it had in the Honda. I tried firing it into the rear corner, rear firing, and finally sealed off forward firing into the cabin of the Honda with much less results than 100% same setup in a SUV -- just saying

 

makes sense. I just noticed all of the bare metal in your picture and that is probably a big cause of it not being loud firing to the rear like that.

 

Each vehicle presents a unique acoustic challenge. I agree that most SUV's are easy to get booming bass out of.

There is a relationship between cabin gain, cabin volume, sub placement, and listener placement.

 

I was talking about the old sub setup that the Honda had which was a JL10w3 in a sealed box on about 200 watts with all the trunk panels installed.

The current 2 - 12" Skars in custom T-Line box on a 1,500 watt RF amp is BEYOND LOUD. Cannot turn it up for more than a couple of mins without having ear pain loud.