I find the best way to sell low level mats is to hang out near the alchemy station in Bazaar (not arcade). Most people crafting 1-2 star items are buying their recipes from the bazaar vendors and when they go to make them may be unexpectedly missing low level mats like swordstone etc. Also these players will usually start asking for their items using /s instead of /1 or /2.

Conversely, i find most people doing their alchemy in the arcade are using the trade channel and WTS functions.
Anyhow, it's worked nicely for me so i wanted to share with others here :)