Animating a 'Channel' number, driven by a another object

Greetings,

I have a fun challenge for you awesome expressions gurus:

I have a vertical bar, showing Channel numbers (from 0 to 800, showing every 50th Channel like 50, 100, 150, etc.) To its side, there's a pop-up bubble, showing the larger channel number with its station name. Also, I have a hand icon, simulating channel selection.

What I'd like to happen:

When I animate the hand position change up and down to simulate channel scrubbing, I'd like the text inside the pop-up bubble to change appropriately to where we are in the vertical bar. So when the hand moves up and down, the pop-up text dynamically changes to reflect where we are in the vertical channel labels. Makes sense?

I could do this manually by creating multiple text fields in a pre-comp and manually staggering them after I animate the hand. However, this sounds like a pain and something tells me there's a great way to use expressions for this.

Any thoughts? I appreciate any ideas! Much thanks,

Redpandavfx