Claying the car is hard work and the SRP is abrasive so don't use it too often.
All car potions with the word 'polish' in them are abrasive and are for restoration, not for regular use. Each time they're used they grind off another layer of paint. Once the hard protective clear coat has gone, that's it.
The SRP is not a wax, it is an abrasive polish and silicone resin sealant.
There are much finer polishes than SRP but without silicone so fresh paint can be sprayed down, these require a separate paint sealant afterwards.
AG "High Definition Wax" will produce a stunning finish.
I think the individual kit components can be bought for less, certainly in larger bottles.
(brother in law ran a car valeting business)