@rrhoover I don't know Olark that well, but PureChat is free for now until September 1st for an unlimited operator package. After that it's $5/month. Installation was just copying and pasting a javascript snippet and the widget's customizable enough for an early startup's needs.
So far I have found the app easy to use and doesn't seem to affect page load times. It won't have nearly the feature set of a sophisticated tool like Olark --for example cobrowsing and an api; but it's enough for a 2 person startup who wants to test whether a system like this is a good investment. I especially like the away message that allows me to return emails the next day when I'm not around. the iOS app is very responsive, too.