$42 a pop: [link|http://www.newegg.com/app/ViewProductDesc.asp?description=33-122-008&depa=0|http://www.newegg.co...33-122-008&depa=0]
How much does ZoneAlarm cost these days? Just dropped by their site, and at the 50 user license, we're looking at $50/copy.
This will do most everything you need for home. If someone is a die-hard road warrior, they're basically fucked - no road warrior will want to carry an extra piece of kit with them above and beyond the laptop.
I look at ZoneAlarm this way: it's like the canary in the coalmine. A great early warning device, but only part of a comprehensive strategy (mine ventilators) to protect the worker.