Wen I first decided I wanted to build a left hand AR everyone tried to talk me out of it. When I said I wanted a left hand AR in 6.5 Grendel everyone told me that I wouldn't be able to get a bolt without having one modified. It was really easy to get the parts they just cost a little more. Mine is pictured in the 264 LBC section.
The parts are definitely out there if a fellow looks. Resale value on the lefty versions usually won't cover the premium price some charge for the parts and obviously the demand is lower. I have a pair of LH BHW railed uppers I shoot. One is a 20 Practical and the other is a 6X45. They are unique for sure. Of all my uppers they are the smoothest I have.
The best firearm for self defense? Any loaded one will do.