Unless you want to buy online and pay a bundle, then advice here isn't going to be much help because a local shop is where you need to go.
You might consider buying several smaller sheets that can ship UPS... that's where you get killed when ordering online, in freight shipping costs.
unless you can find a sheet locally, I have used estreetplastics and freckleface in the past and they are both reasonable and have smaller sheets which will ship ups or fedex.