I put these into items I don't regularly use in battle (those are reserved for resists, hp, mana, etc.). I put them into items that are not heavy that I keep for merchant use only. Three of them has helped quite a bit and most players don't seem to want them.
Add them to a pair of Opal steins, and you'll have +62 cha in 2 items. Enough to get almost anyone best prices from merchants, except for those with a LOT of neg cha gear.