Yep, they're expensive. I think I spent more on metal hardware than I did on framing lumber in my deck. I wouldn't skimp. In the grand scheme of things, you're talking under $100 for a solid footing on which to build a pergola worth much more than that.

Do shop around, though. I think I paid about $15 each for mine.

Other alternatives? Like what?

You could do it the old fashioned way, pin it with a piece of re-bar & glue it. Doesn't do much for laterial strength, but neither do the post base like they sell at home cheapo.