Quality Kava, just like kratom, is very difficult to find. Unlike kratom (where some of the lower quality can still be 'okay'), it's usually either junk or it blows your mind. Fortunately at least phenibut has kick-ass versions with most places you can buy it from.
Unlike kratom, Kava extracts can definitely be a viable option. Although often more expensive, you may need up to 5 times less per dose. Best part of all, these extracts don't create a large dependence or skyrocket your tolerance like kratom extracts do. You get the same effect without having to drink as much of that nasty powder.