Congratulations!  You have found eBay, and are using it to your advantage!  You can buy many products at fractions of their retail and in-store prices locally, and wallpaper border is no exception.  There are thousands upon thousands of designs out there, and once you have found the design that you think will fit your room best, it is time to buy!  But wait!  How do you know how much to get?  Measure the room, right?  Yes, but that's not all.  Almost all wall border has a repeating pattern to it of some type.  When you buy border rolls, almost always they do not stop and start at the same place in the pattern.  When you put it up, you undoubtedly will run in to a few problems, as well, such as accidentally tearing it, not being able to reach certain areas and needing longer strips to get by the problem, in addition to having to match the pattern to start the new roll.  All this adds up to one thing:  needing more feet of border than just the room's dimensions.  Experts recommend buying at least 10-15% extra of length than what your measurements indicate.  This allows breathing room for all the aforementioned challenges, as well as may allow you to have some leftover in case years down the road something happens and you need to replace a section of the border.  We offer rolls at great closeout prices, so our patterns move fast.  We have already had buyers come back needing to buy another roll or two of their design after they put it up and ran short.  Unfortunately, sometimes we have had to say sorry--sold out now.  We truly feel bad that they are now stuck with a partially finished room and have to put a lot of legwork into hunting more of the pattern down elsewhere.  Plus, the border they get from another seller almost for sure will not be from the same dye lot, so there may be anywhere from slight to significant coloration differences.  So the moral of this guide is:  when buying your border, measure once then twice for accuracy, then multiply by at least 15% to make sure you buy enough border, it will save you a headache in the long run!