If you're after bang for the buck, the Kickers are the easy answer. Based on the fact that you plan to run 4 of them, I would say that's probably the best choice for you.
The RMS power rating of a sub has nothing to do with the amount of power that you "need" to run to them to get the most output from them, it's only how much power the voicecoil cna handle from a thermal perspective. You have to consider the enclosure when you're talking about sub output for a given amount of power because that is much more the determining factor than the amount of power the coil cna handle. Most subs can reach their full excursion with much less than rated power in a large sealed box.
IB installs are not for you. They greatly reduce the power handling of the sub to get the best out of the driver in terms of a smooth response. They also sacrifice a little bit of peak output.