Kirisun is a pretty big company and has a good reputation. The Kirisun radios I've held at the trade shows were quite nice and seemed well built. I wouldn't rate them down with the Baefong and other low end radios, they are much better than that.
Check their website, I haven't been able to find a K800 model. Either I'm missing it (the website is loading slow here), this isn't on their site, or it's a "questionable" model. Doing a google search comes up with the e-bay ads and a few other non-Kirisun pages.
I'd be cautious about buying one off e-bay though. Too high a risk for a knock off.
True Kirisun stuff is pretty good.