Even with selling 99 of them you would only get 79,200 gold as profit. Although the leveling just might be worth it and you never know if buying 99 of them will unlock another item in the shop or somewhere else. Since I am there right now I'll give this a try and see what happens
Unfortunately I have found nothing extra for it in any of the shops. Nothing extra from any of the vendors nor have I found anything in town. Only thing I have gotten is level 40 for Luciana and 44 for Tarabulla......and well roughly 79K in profit later down the line.