As amusing as the thought of good speakers on a beanie is, it’s hard to take your word that they’re any good (though at $20 does it matter?), as you used them to replace a pair of Beats by Dre. These are presumably the “$100” headphones you mentioned, which is to say they’re $10 headphones that you paid $100 for because of the brand name.
But besides all that, your thought experiment of high-quality headphones paired with high-quality headwear is… an odd one. Perhaps you weren’t aware, but very few people wear hats or beanies all the time (or all the time they would be wearing headphones). Much less the *same* hat/beanie all the time. Your posited buyers of expensive speaker-laden hats seems to be limited! Fortunately, the world has already found a solution for this: bluetooth headphones… but you also wear a hat. Since physically connecting the two doesn’t really add anything, and limits your options.
(As a tip: for other “revolutionary” electronic devices like this that you aren’t finding in Silicon Valley despite being so into the “tech scene”, you should probably check out the Sharper Image store/catalog, located at your local mall.)