I think Razer has a left handed deathadder, i know some friends who are left handed who still use the mouse with the right hand. I personally prefer Logitech mice but i'm right handed and like the right handed mice, there are ambidextrous mice but if you want a left handed mouse (as in ergonomically designed for lefties) the Razer Deathadder is the only one I know of from a reputable brand.
For keyboards, I'd avoid Corsair on the basis that the keycaps are trash. I bought a Corsair K70 Lux and have had to buy the double shot PBT keycaps as a £40 addition after the fact as the original keycaps were breaking so often and buying individual keys off Ebay was making it seem more beneficial to just buy the double shot PBT keycap set from OCUK and do a full replacement. Much better typing experience.
As a leftie, if you get a desk mouse pad (super large one) then you'll benefit from the logo normally being on the right so it wont get in your way.