Helloooo,
On my radio, the plastic #1 button has peeled slightly revealing white underneath. I'm not looking to remove all the buttons and sand it, but don't wanna take a permanent marker to it either. Any product that can do a quick touch up on it?

 

You could try a sparing use of plastidip spray.

These headunits are really cheap on ebay - might be in your best interest to just replace the whole radio, rather than trying to get a permanent fix for that one button.

 

Man... $150-200 for a 10 year old unit is not particularly cheap...
The screen on mine is starting to delaminate, so I was looking for options.

 

Geez - for a Benz, any trim piece is that much, let alone an entire headunit. I'd consider it a bargain.