Someones outfit was worth 1 billion.

I noticed someone had an outfit that was literally 1 billion something. All of it was from a single t shirt that costed 999,999,999.

If i make a t shirt thats like 2 robux and then i buy it for myself but change the price afterwards to 999,999,999 as well or something, could i do that too?

Im thinking that's how this guy got his outfit worth that much. I've never created any shirts before so, clothing makers of roblox, is this possible to do?