Alternative to Kirby Heavy Traffic Shampoo Pre-Treatment Spray?

[abcvacplacentia]

I'm about to break out my Kirby G6 shampoo system to clean up my carpets and I was wondering if anyone knows of a good (cheap) alternative to Kirby's Heavy Traffic Shampoo Pre-Treatment spray?

You can buy a 22 oz. bottle on Amazon for $18.51, which seems pretty expensive to me.

https://www.amazon.com/Kirby-Heavy-...6NEFzckLsBh4kHykw4eRRA9BRSRAtO87XMbz6CmbOi5MO