Release
It's not questionable business to pass along drastic cost savings to your customers when compared to average retail pricing of similar product from your competitors.
At 29.99/doz, they could double their net profit and still save their customers $20/doz on average for similar named brand.
The bait-and-switch term wasn't intended to be taken literally... they obviously can dictate whatever introductory pricing they want (within reason). It's also worth considering that should my scenario be somewhat similar with regard to them "testing the waters" for potentially a more long-term deal, based on consumer feedback and demand (which is perfectly legal) then it could be rationalized that increased costs for overhead, shipping, materials costs, inventory restocking, etc. would almost be expected.
It doesn't need to be said, but even should they go above and beyond their across-the-board 14% profit margin on a particular item doesn't mean they're ripping their members off. They're within their rights to dictate pricing and make more profit.
Another potential angle is it's not out of the question that Titleist, Callaway, etc. might be looking at the manufacturer for patent infringement reasons, especially if they sense that the sudden popularity of these balls doesn't wane and could put a serious dent in their own golf ball sales. In that particular scenario the manufacturer would be legally obligated to inform the wholesaler of their product about the potential legal inquiry and that would likely also cause a situation that Costco would want to avoid altogether.
I just don't think Costco up and decided for no apparent reason that they don't want to continue pursuing sales of what was obviously a great selling product. Something else going on imo.