try
www.dama.com.sg. 4' X 6' should be ~$50 for 4mm clear. every mm thickness more == more expensive. Dama does customisation for cutting/polishing. They ain't the cheapest around, but the products do look good.
I'm trying to get 24" by 16" x 4mm clear with corner drilled holes. If anyone has good/cheap lobangs don't mind sharing yeah?