Yes, but they are nosebleed expensive and are shrink-wrapped around a set of threat vectors common to all their customers.

The privacy concerns with commercial endpoint stuff are comparable (though not the same; with some endpoint tools, it would be difficult for a manager or a random IT person to snoop on what you're doing). The concern about operationalizing is mitigated somewhat, but only if all you're doing is malware/public-threat-feed stuff.

I am not sure rolling your own will be less expensive.

It depends on what you’re trying to accomplish, but commercial distributed endpoint protection would not be in my top 20 projects for any startup I can think of working with.

That obviously depends on many factors Dropbox is not exactly startup though :)