Quarter inch usually sells for about 40% more than half inch. Less costs
more. WHY?

I don't think my local HD or Slows stocks it.

The local Slows does have some paneling at $10.

If you can find a drywall supply company you might be able to get a better
deal on the 1/4" but it will still cost more the 1/2".


Colbyt

It may be a specialty. 3/8" is common and is about $6 a sheet.