I never charge by the roll, its always by the job. Too many variables in wallpaper. $1-$2 a linear ft of border is the norm, only exceptions would be if its over 16" wide, a paintable 'frieze' type, or needs to be inlaid. I also charge extra to prime the wall where the border goes, but if its over paper, I don't.
The paper part can get tricky. It depends on your skill level, type of goods being hung (pre-pasted mass market PBV, or block print Brit pulp, or $45k Zuber scenics, etc.), the difficulty of the area being hung (2 story stairwell, cut-up bathroom, etc.), amount of prep needed, and what the market will bear in your part of the country. I would start with figuring what you need to make per hour or day, and go with that. This way, your being paid what you need whether the job takes 2 hours or 2 weeks. As Teetor said, I always try to get at least $300 per man per day to cover wages, taxes, insurance, overhead, yada yada yada.
If you are serious about hanging paper for a living, join the National Guild of Professional Paperhangers
NGPP or contact a guild hanger in your area. This is the best resource for wallpaper in the USA.
You need any more info, email me.