This is Just Such a Good Idea

A company called SarcMark has developed a proprietary punctaion mark to denote sarcasm.

That is like such a good idea.

Yes, that is the symbol, and it's looks like, but isn't a bit of Hebrew cursive.

This is clearly an essential part of any repertoire, and well worth the $1.99 the maker wants to charge for its use.

Sorry, but if you need to mark it as sarcasm, something is lacking in either the writer or the reader of the phrase.