Another great place to check is Crutchfield. The have good sales and most of the time free shipping. Kicker CompVR'* are good subs, but, I feel their are better ones out there for the money.
If you are looking to stay in a budget, look for subs with a good SPL rating.
For example Sub A has a 90db rating and Sub B has 93db rating. Sub B will typically place twice as loud as Sub A given the same amount of wattage.
Also look for a good 4 channel amp, you can practically run an entire system off of one amp.
Most important shop around, and do your homework.
02 Se with a few mods,
Coming Soon 1.9'* OR pushrods and other stuff