Not exactly a new invention, not even a new design.. Wall mounted, rail mounted and even window mounted BBQs have been around for many a decade. We even had a tow bar mounted one back in the 70's. Marine BBQ's are very similar..
If you want a cheap one just buy a metal flower box and cut some grill...
If you want innovation then this one takes the prize for wall mount and great design and came out about 3 years ago..