I have a set of Claris/2400 shifters, the new 2300, that are sitting in my garage. 8 speed, new take-offs, but sales in this forum are not allowed for basic members. I would direct you here for your lever - don't think you'll find it for less anywhere else aside from Craigslist, and it would be a rare find. Only sold in pairs though.
What kind of bike is this, how old, and is an upgrade worth considering?