Not sure if this has been done but doesnt take too much thinking to figure out. This is a way to win those BoPs or BoEs without pissing off your group or being on master looter.
The trick is that you go to an instance around your level and roll need on an item you already have. Once you win the item you can DE it or sell it (if it isnt soulbound) after the run.
~BoP Items~
Equip an item that is about 10 levels below your current level that uses the same slot that the BoP item would use. Ten levels because most players will sympathize about your crappy gear and tell you you need an item more than another player. Once you reach a boss in the instance that will drop the item you want to DE, like Emberstone Staff, you will have the rights to roll need on it. Once you win the roll (assuming you have no competition) you equip it as one would normally (dont forget to act excited!)then once the run is over you DE it and get your shard to sell. Then you can equip your other Emberstone Staff. You can rinse and repeat this technique until you are done going to that instance. (Be sure not to do this with the same players)
~BoE~
Set items usually work best for this. Like Shadowcraft Belt or Defias Gear (one normally drops every run or two). You do the same thing as before but this time be sure to carry along your already soulbound item. This way once you win the roll you can equip the souldbound one you already had (people tend to inspect armor after a need roll to make sure you aren't trying to sell it). Then once the run is over you send the item to an auction mule and sell it.
Enjoy!