For a custom enclosure, what type of PVC and where to buy?

I'm planning to build a few custom enclosures soon. For weeks, I've been searching for PVC options without much luck. If similar questions have been posted before, please help as I didn't find by searching here yet.

I plan to build dimensions around 42-48" wide x 24-28" deep x 18-42" tall.

Is there a certain type of PVC sheet I should be looking for?
is Expanded PVC a good option or is there another type of PVC sheet I should be looking for?
Any tips on where to go to find the best prices on 4'x'8 sheets?

For PVC 4'x8' sheets ~1/2" thick, I've seen prices range from <$100 to $500+ and I cannot decipher which type of PVC to use.

This 12mm 4'x8' expanded PVC sheet is $152 https://www.curbellplastics.com/Shop...al-Print-Grade

This 0.5" 4'x8' Type 1 pvc sheet is $325 https://www.eplastics.com/PVCGRAY0-500EXT48X96

Thanks in advance!!

You can find 4x8 and 1/2 inch thick at home depot and you gonna need 1/2 inch thick.

Some Home Depot’s like mine do not stock it and you have to order it online.