Looking for a Commercial dual 18 subwoofer for Sound Renfocement

I am setting up a sound system for a church and I need a suggestion for dual 18 inch subwoofer that would be up to the task. I will be using it for bass guitar and kick drum.

I notice that it takes a lot of power to reproduce kick drums at a decent volume. I have heard many systems where once everyone else in the band starts playing the kick drum is drowned out. I dont want this to happen.

The building is a rectangle about 50 x 100 feet with a triangular ceiling (starting at about 10 feet) reaching approximately 30-40 feet high
I will be using a EP4000 to drive it. I have a budget of up to $2000 maybe less.

Any suggestions????

I am thinking about these:
JBL SRX728S JBL :: Product

EAW LA128Z EAW LA128Z

ASB6128V JBL :: Product
 
I suggest you get a sound level meter.... go to some venues and measure what level you think you want music reproduced @ so you have a ball park target... Then think about what distance you want this to be reproduced @.

With a target then you can think about how many boxes you need to get there.

Have you considered DIY... because you can build 6 2x18 for 2Gs... Run with the same amount of power... the 6 boxes will be 6 to 12 dB louder and far cleaner than a single 2x18 near your budget.
 
I'm pretty sure a lot of the punch of a kick drum comes from harmonics, so don't neglect the mid-bass. Hook up a spectrum analyzer (use the PC or laptop) and look at what comes out of the drums and bass. You may not need a true subwoofer at all.
S
ince these subs don't have to be movable, maybe a pair of horn-loaded subs is the way to go. Have a look at the designs at Speakerplans.