Per my Labor Contracting Book: a single roll ow wallpaper will cover approx 36 square feet. Allow 6 square feet per roll for waste.Therefore use 30 s f per roll in determining number of single rolls. Here is the kicker: For patterns that require matching, allow 25 to 30% waste. For large bold patterns waste can be as high as 50%. So, you are still paying your per roll labor fee even if there is 50% waste per roll. Consider "drop" amount in inches when purchasing your wall papering and this will reduce waste and make $ per square foot or roll higher.
Depending on the market, mine is a going rate of 25 to 30 dollars per single roll of paper. Removal is based on application also and can be higer due to more labor intensive job than actually applying the paper.
YOU CAN SAVE ALLOT OF $$$$$ IF YOU REMOVE THE PAPER YOURSELF.
Now, the following is a hypothetical 12 x 16 room that needs wallpapering and the painting of the trim and ceilings. Your looking at 420 sf of wallpapering figuring the need for 7 hours, painting of the ceiling, painting the trim base boards and one door and the window trim. The total job will take 19.1 manhours, and $1300 for material and labor.
When hiring a contractor, especially wallpapering and painting contractors find the ones that charge by the roll or square foot NEVER by the hour.
So, your homework is to determine the square footage of the area to be wallpapered, the waste factor, then the amount of single rolls, then multiply by $30 and you should get a pretty competitive labor price for your job.