Replacing sidewalk section

I have one section of sidewalk in front of my house that is severely lifted. I already ground the edge myself once but it's time to cut the tree roots underneath and replace. I have done a fair amount of DIY concrete work but I may want to have this done by a pro so it's done fast. About how much would this cost? It's just one 3' section that needs replacing. Also, I see a thin vertical plastic strip embedded between some of the sidewalk sections at the control joint. is this some kind of isolator? I don't think it goes all the way through the slab because I see no movement at these joints. Thanks