Science in Sports (SiS) Beta Fuel (best price I’ve seen is about $1/packet on sale)
Maurten
Infinit Nutrition - this is what I use. I got a free consult and custom-made a formula. It’s about $60 for 25 servings, and I only use it for sweet spot and above workouts, or endurance rides longer than two hours. For short endurance rides I try to go fasted, otherwise just Gatorade.
There are many more out there, and an entire thread on mixing your own carbohydrate drink.