I had a small area to wallpaper recently (2 rolls) found it near impossible to get a professional to do the job (interior designer didn't even know someone who could do it). Its slow work (if done right) and professionals prefer to stick to painting where they can get more done in the same time.
Eventually found a guy who does it in his spare time (used to wallpaper full time in the US), unfortunately this was Cork.
Going rate was €140 for a day, he spent in excess of 4 hours at the job, I was happy to pay him for the full day because it was done correctly.
I had contemplated doing it myself but speaking to the professional I was lucky I didn't. It seems that expensive paper is harder to hang that stuff bought in the likes of B&Q and should only be undertaken by a pro.
Really love the end result. Must give the guy a call as decided to use wall paper in another room on a feature wall.
Hope this helps.