When is $300 Less Expensive Than Free?
$300 is less expensive than free when the $300 is an investment in something useful.
Given how much is available to us in this day and age for free it's easy to get sucked into the free-is-better mentality. Why should I advertise when I can post to Facebook? Why should I pay for service when I can do it myself? Why should I pay for a car, and gas, and insurance when I can walk?
That last one is probably more obvious than the first two, you should only pay for things that bring you value. That value can be in the form of profit (or risk mitigation in the case of insurance), time savings, better performance, expertise, quality of life, etc.
Local business often ask these questions to service providers and publishers. Publishers sometimes bring this up when thinking about their own business. The example in the video wasn't as much about the cost as it was the effort - that is, the cost-benefit of spending time, money and energy.
That publisher thought having a Facebook page would be less effort than managing a digital presence (website, Facebook page, email newsletter, etc) with comparable benefits given they weren't making any money online at the time anyway. Good thing they reconsidered their position.
Or, as Zig Zigler would say, they didn't change their mind they made a new decision based on new information.
Be careful not to get stuck thinking exclusively about the price of something when you're really concerned about the cost.