Geometry Dash YouTuber MatMart has placed a $1000 bounty on the lost level "Ice Carbon Titan X" by Roadbose, also known as Roadkiller.
Ice Carbon Titan X is an extreme demon that was deleted after 3 days by its creator, Roadbose. Only the first 5% has been restored, with the remaining 95% being a mystery.
As such, MatMart has decided to put a $1000 bounty on the level for anyone who can find the level. He also said he would distribute the bounty to anyone who could find more information regarding it.
The full version of Ice Carbon Titan X was only played by about 300 people before it was deleted. Some players who completed it in practice mode admit that they don't remember much about the level. This means that unlike the Element 111 Rg situation, Ice Carbon Titan X cannot be restored by memory.
With all this taken into situation, MatMart considers this large bounty justified. If this level is found, it would technically take the title of most expensive Geometry Dash level.
You can watch MatMart's video on the matter here.