Ive been shopping like a wild man these past few weeks doing exactly what you are looking to do! I am doing a complete swap out of everything from head unit to sub and eventually adding headrest monitors for the kids. I have everything in the house ready to go, just waiting on a friend of mine to help and to let me use his heated garage

This is my list of items bought in case you wanted to know..

JVC KW-AVX830 $397 (has a detachable face!)
Jvc RM-RK252P Remote $24
Polk Audio DB6501 $116 (fronts)
Polk Audio DB651 $59 (soundbar)
Polk Audio AA3085-A $81 (replacement sub for the factory in the stock enclosure)
Boston Acoustics GTA-1005 $250.00 (50W x 4 & 400W x 1 )
Boston Acoustics GTA-RSL Remote Gain Control For GTA Amplifiers $20

EFX Amplifier Wiring Kit 4-gauge w/Patch Cord $30
EFX 17-ft. Stereo RCA Patch Cable x2 $18
Dash kit, antenna adaptor and PAC $110
Dynomat $24

Total $1129.

Obviously there are a couple things in my list you don't have to do like the remotes for the amp and the head unit. The main reason i went with the JVC was because JVC is the only company that offers 7" screens that are completely detachable. Everything else i install in the jeep will be all nice and hidden and utilize factory locations.

You can also save money by keeping the factory sub enclosure and just replacing the factory sub and adding an amp like i am doing.

As far as the headrest are concerned there is a guy somewhere in these forums that did it and was able to find headrest monitors that have built in zip covers so you cant even see them when installed. A search of the forums will pull it up.