unless you have a power antenna, the blue/white wire is doing nothing where it is currently hooked up. cut it and use it for your amp's remote wire.
keep the power cable on the driver's side and run the RCAs down the passenger side.
the other thing you need to do is update the chassis ground. You'll need to run at LEAST a 4-ga wire from battery negative down to the "framerail" to one of the bolts holding the mount for the motor mount. make sure you clean the paint off on the bracket when you do this.
I don't know what kind of power you're running, but another tip is to NOT mount the amp directly to the sub box. the vibration of the subwoofer WILL damage the amp eventually.
the key important things are:
SEPARATE the power wire from the RCAs or you WILL get noise.
make sure you have a good ground path. Use a multimeter set to "ohms" to test this. test while the Jeep is running. if your ground resistance is over one ohm, you'll have problems in the future.
that $120 isn't bad considering all the work that goes into doing a proper install. I would give it serious consideration, unless it's at best buy or circuit city or some other big-box retailer.
any more questions or standstills, PM me. I do this for a living