JL W7 vs. Earthquake Magma

Brahma 12's would be a cheaper way. They are darn good subs as well...even cheaper would be the shiva's

Also Eclipse subs are..well the best...lol.. thats if you want to spend lil more

First off, I wrote this Very Long Reply to help you as much as I can, so please read it through and gain the knowledge that took me a while to acquire. The brands that I will show you at the bottom are great brands that can truly hold up against the Industry's best. Once you get familiar with those brands, do a search online and see who uses them and why. Now second, how much money do you wanna spend?  If it is a lot you wanna spend for a great SQ/SPL system, most of the brands stated (JL, Eclipse,...) will go a long way. If you are interested in having an awesome SQ/SPL system , there are some more sights you should check out RIGHT NOW!!! There are a couple of companies that make Great subwoofers for less than the cost of a JL or Eclipse sub and also have great customer satisfaction teams. I have a list of companies under this paragraph that will help you onto your quest for sonic bliss. Notice that the most expensive and best sounding subs have a huge/deep  motor structure(magnet) and a large amount of Xmass("excursion"- what moves the air and makes BASS!). The Magmas one-way excursion is half an inch(13mm) with a Measly 500 Watts RMS, while all of the companies listed beneath have models that regular 18mm Xmass and a 2.5" - 3" full stroke and can definately take more wattage and sound window-shattering while doing it.

First, Resonant Engineering: http://www.respl.com/flash_index.html             They have GREAT SUBS for all applications, make sure to check out the pics! Definately check them out! If you want a place to buy them, check out http://www.visionaryaudio.com/RE.htm

Second, Elemental designs(Best Buy): http://www.edesignaudio.com   They also have great subs made by geaky car audio Freaks! 3 different models in fact, the K, the O, & the A. The A is their top woofer and the MOST EXPENSIVE @ $315 for the 15"!!!! It contains Dual Spiders, a 200 something ounce magnet and a flat-piston cone, like the rest of the line. And all the subs are backed up by their 3 YEAR WARRANTY!!!! For this price what is being purchased is unheard of. You can purchase this companies products on their websites.

Ricetech, which subs are you getting from Elemental Designs? The A's? Well whichever you are getting, make sure you have a box "BUILT" for them. Don't go with a prefabricated one. Because if good money is being spent on some great subs at least compliment them with a manufactered spec box. If you are going to put them in a ported box make sure you have an amp that has a steep crossovered Subsonic filter. If you want I can help recommend a good class D amp for any application.

Just a heads up.  The ED 15A sub is on backorder for quite a while. 

I'm with Maxst on recomending the Brahma's.  They cost a little more than the A, but have a little better SQ.  Output should be the same.  You can buy those from Visionary Audio as well.  It is owned by Marshall, a friend of mine.

BTW, the XXX (by RE) is a VERY similar sub to the Brahma. 

Sounds pretty good to me!

http://adireaudio.com/mobile_audio/drivers/brahma_series.htm

theres the Brahma- very good stuff