It depends on where you get them mattius. i payed $35 for one light and $88 for the other, 35 is dirt cheap while 88 is a bit expensive.... sadly since i could not get a matching pair the colour is a shade diffrent, mainly in the center circle... ones bright orange while ones a duller orange/redish but it's no biggie lol I also had to buy a tube of silicone, all clear stuff cause it's cheaper then that skalfilex stuff and a LOT cleaner & easier to use, god by the time i wash finished i had the crap all over me.
And as a tip for any one who trys what i did hear are some points to remember.
1. you MUST take off the center peace at the rear or you will break the side peaces.
2. You must take the side peaces half off before you can get the lights out
3. HAND SCRUE, these nuts wil thread very easily
4. The threads on the hotplate lights tend to be shorter then the s1-2 version so if your down at the wreckers get your self some skyline "grey" caps that hold the carpet on in the boot, or like me you can just put the old one's in the vice
5. When doing the conversion there is only one thing you need & that is the skyline wire harness (the thing that holds the bulbs and conects to the cars power) you may be able to get some of your original leads to fit like me but you MUST have at least one skyline (hotplate) lead so you can replace (from my experance) one bulb holder on each side.. they simply will not fit not matter how much you cut the tabs (witch you must do to get the originals to fit) if you do it the hard way you will need either a wire clamp set or enders, these join wires tougther
6. Skaliflex is a sh*t to clean off the back (witch you must do) but i found that turps or any other car cleaning engine spray will do the tick.... but you need about 5 cans so it's probably cheaper to buy a thing of turps and put it in a cheap spray bottle, don't delude your self it will take a good half hour to get each side clean and another 10-15 minutes wiping all th crap off your car since it leaves a dark stain on the paint work untill you clean it
7. R31 pinnys are prone to leaking (even with hotplates) so remember to put as much silicone on as possible...and ya you have to put the side plates and the lights in at once :p
That about covers it
it's not hard but it will take you a day to do....
$120 or so for the lights, 50 for the garnish