We are doing Foundations this year and have enjoyed it very much. Next year, DS will do Essentials which *I* think will be even better for him.
Our community doesn't charge a facility fee nor require us to buy much. The MUST HAVES: tin whistle, either the guide (book $60) OR the app ($15 per cycle). Each child needs a whistle. The guide is used by the parent only.
I like the timeline cards because we can read more about the events that interest us, but they are not absolutely necessary. Once you are in the community, you can sign up for CCConnected and use their file sharing section to download all the music and visual aids your heart desires. It's $6 a month, but you can download everything in one month and then let it lapse. The CC store has lots of lovely and useful stuff, but you don't have to buy it all. I'd suggest getting into the classes before buying all the pretties.
CC has been a real plus in our homeschool this year, but I only have one child. Having two in the program would be expensive. Best wishes on your decision.