FlatOut Off-Road Multi-Purpose Tire Sealant - Prevents and Repairs Flat Tires - Seals Leaks - Contains Kevlar - Tubeless Tire Sealant - 32-Ounce Bag - Pack of 1

Work almost instantly, and will plug current issues. I have it in all my tires. .https://a.co/d/08vWQLDc

Everyone has different definitions of expensive, but it should only be about $25. I have the XP4 and this should be enough for 4 tires. https://www.amazon.com/dp/B07PWBFTRJ Also, slime "expires". I believe Flat out lasts the life of a tube.