Just make a small trading system, like at the end of a Strike or Raid you can "Offer" to trade your obtained loot from said boss with another person for the same quality loot I.E. if someone got an Atheon's Epilogue and has no desire for it, but the guy who got VoC wanted Atheon's Epilogue, they may exchange during that time and that time only. Exotic for Exotics Legendary for Legendary Rare for Rare Uncommon for Uncommon Common for Common therefore you wouldn't have "Beggars" who spam the "offer button" to people who got goodies or people who post "WTB Ghorn" or "WTT Hawkmoon for Icebreaker, fully maxed rdy to go" junk