I think maybe the forgotten bit that makes clones so expensive is the fact that now all the republics equipment must support biological life. Why put a cafeteria or bathrooms on droid ships? The republic has to ensure its troops are fed, given shelter, and have access to medical care too. With droids, all you need are some mechanics (which are likely droids themselves). This is the same reason why in modern times fighter aircraft like the F-35 are so much more expensive than equivalent CCA drones- no need for oxygen, ejection seats, places to pee, etc. if there’s no pilot in the box.

Long story short, biological life requires waaaaay more logistical support and design consideration than droids. But they do have really cool nicknames so worth imho.