Call a couple body shops, they should be able to tell you how much it will cost to install the junkyard part you provide. Just be aware that the paint won't be an exact match, it will probably be good enough since.it is an older car anyway. I don't imagine that the labor will be too much if you don't want it painted.

The rear right panel on or 2010 Honda Accord is torn and falling off

I would dream we can buy a replacement piece from a junkyard in matching color and pay someone 200$ to attach it, but fear if I call dealers they will say $1400 plus another 400$ to paint it.

Any advice? Ideally replacement part would be same color but don’t care if it has a few nicks or scratches our car is far from perfect.