Good luck finding them first. or rather easily find them. I would check the sonics and woofersetc out there. http://www.sonicelectronix.com/item_18016_Orion-HCCA122.html
Secondly, TundrSQ is 1000% correct on the electrical upgrades. You are talking adding batteries as in multiple and at least one HO alternator.
If you can get the sub in dual 4 ohm coil configs then a single amp will make it easy, otherwise you are looking at a high power at 2 ohm amp like a JBL GTO line or others.
If the dual 2 ohm coil is the only way you can get this sub, and you are going to run 2 of them, look at running 2 amps.
for the money they want for those HCCA subs, I would look at the Sundown woofer lines. Like the SA or the Z.
3 of those will cost less than 2 of the Orions, give you the cone area of just about 2 15" subs. 2 of those is less than 1 of the Orions
I run the AXIS line equivalent from TC Sounds. Quad coil shorting ring high power and output, small enclosure 30mm excursion 1 way linear. About the same dollars per as the Orion
Here is the thing, running kilowatts of power becomes very cost prohibitive. And as you add more and more power, the return is less and less. For every 3db of output gain, you either have to double the cone area or double the power. 3db is not a lot. plus you start to fight thermal compression. Thermal compression is when you are giving the woofer a lot of power the woofer coils heat up increasing the resistance. This in turn reduces output so you end up fighting your woofers to get louder.. Physics tends to bite you in the butt.
My suggestion is to run 2 or 3 of the cheaper subs in a properly designed enclosure. Run a single 1.5 to 2kw amplifier that can handle the load you are wanting. See if the volume is adequate for your needs. Chances are your factory electrical will handle the amp unless you are running around with max volume and tone heavy music. You could always add a second amplifier.
I like 3 subs for these kind of installs because more motors means cooler coils which reduce the compression. it's cheaper to add a second battery and a battery tender at night than buying a 400 dollar 200+ alternator. and other batteries.
Good luck!! I have been through this with my son. Can try to help as I can.
TundrSQ also had a good question... What are you running besides a 140db+ subwoofer set-up?