Actually, I have been visiting a thread with this suggestion, and a Moderator (gordonrox24) replied, with words also directly from Roblox.
He said this:
"Refunding Items has been suggested for quite a while, and maybe it will happen one day. What may be more useful is a "try before you buy" feature. This feature is tough because it requires Roblox to spawn money, and we don't like to introduce money into the economy like that, and will will introduce Robux/tickets into the economy in large quantities" |