Do they sell tarps

Yes

Depending on which tarp and it's intended use - YES...

I bought one in the paint section

I think they do. You might th check in the paint section or auto care section.

They sell plastic drop cloths I don't know if they sell canvas drop cloths or not

Not sure. They sell just about everything under the sun. You can call customer service & they should be able to tell you better. Sorry I couldn't be more help.