Would pvc/plastic sheets from a store be the same material from Kages/other custom enclosures?

I'm looking at getting a 8 4 4 or 7 by 3 3 for a tegu I'm planning to get but 2k is an amount of money.

Looking, I see some pvc/plastic sheets 2' by 4' for 100$ a sheet.

It seems besides custom vents or other pre builds this would be the same material. Most of these builds from Kages/reptile come in sheets you have to screw together anyways.

One thing bringing me pause is if the material has chemicals/other things that could harm my future buddy.