8x 8x8 WS2812 Matrix $2 each = $16

ESP32 $3

1x some acrylic to laser-cut a case in a makerspace $5

So $24 total. The screen would be much larger than the Busy Bar version, which could be a pro or a con, depending on what you want.

If you need the smaller back screen (I don’t see the use because I would control it from a computer anyways), that would add another $3 or so. The buttons are basically free but if we assume $3, that’s $30 like you said in total.