https://wiki.project1999.com/Special...ument/AllItems
Kind of a terrible page since it is missing the primary information (instrument modifier) but it's all we've got AFAIK.
For Brass (not on Green) Conch Shell Horn (21) is really cheap, and Immaculate Shell Horn (24) is expensive and the best you can get. Also watch out for fake Horns that are actually Wind.
To do the math for if a new instrument would increase your damage, play it with no modifier and then times that by the new instrument's modifier, rounding up if the decimal is above .5
Anyone interested in Green's Brass instruments, as far as I can tell the only upgrades are the Efreeti War Horn (22) and then the Sky quest that requires it and rewards Denon's Horn of Disaster (24). Those mobs are generally a 7 day respawn so good luck with that. Also worth noting that Denon's Horn of Disaster is a primary only instrument and twisting instrument swaps with some secondary and some primary instruments can be awkward.
Love, Nonon Manabot
P.S. If you've got any questions you can send me a tell on Blue the 3 hours a week I am online.