Parking sensors installation

[Nick B]

Hey guys. I dont have parking sensors on my lexus rx350 luxury model. I was wondering if anyone has done it before and have any recommendations for me. I rang lexus service centre in parramatta today and they quoted me $800 just for a rear bumper(i think its expensive) and they said that they can only do rear bumper and impossible to front as it is a Grade A model which i dont know what that means. My mother drives a 2012 rx270 basic model and it has front and rear sensors. I also have a gs300 rd gen which has sensors too. Im actually pretty surprised that my 2015rx doesnt have. Doing it myself is not an option for me as im pretty bad with cars. So my question is if the price is fair or not and if nit is there a place in Sydney I can have it installed for a better price.  Also do i have to get original lexus sensors or any sensors will do the job. If not then I dont mind having it done at lexus. Thx heaps.