What does your shop need an hour to keep your doors open ??
That's the real question. What others are getting is only gonna give you a hint as to what to charge in their area. We might get $2.00 a square, while some other guy might be real slow and get $5.50 a square. There's no going rate. Besides, out here on the open forums, it's hard to tell each other numbers without the possibility of your customer possibly seeing it or even your competitor.
If all you're doing is going 8' high for 20', that shouldn't be any harder to figure out then what it would take to lay vinyl on 5 4' x 8' panels and then trim them.