I've been told by people who do this sort of thing that an algorithm change in the last 6 mos. or so has made organic buzz much harder to get going on FB without paying.

To a small extent. Yes, they make you pay to "promote" a post higher in a user's timeline who simply liked your page.

But I'm talking more about organic buzz, whereby for instance your friend shares something from a page or talks favorably about it. There is no option to pay to promote those shared posts. The priority of those shared post depends more on how good of a relationship you have with your friend and how much engagement facebook thinks it will get form it.