I Could Have Surely Help If You Are In KHI.... Thats True That It Will Empty Your Pockets..... Booster And Master Cyl Set Cost 2k And Whole Front Assembly Cost Around 3-4k....Its Not Like 20k....! Don't Know About LHR Buts Its How Its Here..
Anyways...Yea Thats The Way Of Checking Booster But Sometimes Booster Is Leaking Vacuum Internally As Diaphram Is Not In Great Nick....!! Well Hard Pedal Also Caused By Air Inside Braking System....!! Both Can Be Reasons Of Hard Pedal.....!!
Just Make Sure They Bleed All 4 Brakes Good Enough And Fill With Quality Seikan Brake Oil.........Use Original PS Brake Pads As You Already Did.....Rest Left Is Booster And Master Cyl Itself...Nothing Left...!!
Conclusion Is That PS Cars Shows Things Like That Commonly.....!!