I've heard there's better instruments than what the regular bard vendors sell. Is there a vendor that sells them? Or where should I look for to loot one?
Assuming you're Occlo based one (or both?) of the marble workshops next to the bank has GM tambourines for 400gp. They give a bonus to barding success. There are also magic instruments dropped by mobs that are more effective against certain mob types, but that's something I've yet to explore so someone else will have to expand on that.
Players and player vendors sell gm crafted instruments which give a 10% success chance bonus over npc vendor instruments I believe. Monsters drop slayer instruments which give a bonus to success chance to whatever the instrument slays. Instrument slayer instruments follow the same drop chance as weapons, which is detailed here: http://uorforum.com/threads/renaissance-guide-to-slayers.1601/page-2#post-25708
