Mr Hartley is certainly correct in saying the best bass is expensive.
As Mr. Harley put it:
Third, accurate bass reproduction is expensive. The lower the frequency accurately reproduced, the more expensive bass becomes. Note the word “accurate” in both sentences; you can buy a $500 loudspeaker that has output below 40Hz, but it’s unlikely that the bass it produces will be accurate. Realistic reproduction of the bottom octave (16Hz–32Hz) requires large woofers, which in turn requires a large cabinet. The larger the cabinet the more prone it is to vibration that will color the sound. Enclosure vibration colors the music tonally and destroys music’s dynamic structure. The solution is to build heroic enclosures that don’t vibrate, but such enclosures are extremely dense, heavy, and expensive.
I can attest to this part, "Realistic reproduction of the bottom octave (16Hz–32Hz) requires large woofers, which in turn requires a large cabinet.," but the concern about enclosure vibrations and their amelioration is, if not unfounded, then blown out of proportion - certainly in regard to expense. It’s the typical hifi-adage of "you get what you pay for," and while bigger drivers and cabinets are more expensive than smaller ones, all things being equal, the final cost of refrigerator-sized (or bigger) bass cabs needn’t be excessive - at least not relative to the amount of money being spent in the high-end arena on cables and other accessories alone.
The first and foremost challenge in achieving great bass reproduction (other than implementation) is the need for sheer size (and/or number of subs), but many an audiophile would rather shell out ungodly amounts of dough than have size have its unapologetic way, and this is the real crux of the matter; cultivation in the extreme, within a physically limited speaker framework, rather than, conversely, going by form-follows-function. How about an Infinite Baffle bass setup with 4x18" drivers per side (that is, two of them) taking up floor to ceiling, or a pair of large horn subs with everything ranging from 15" to 21" drivers? If one wanted to buy these or similarly pre-build from, say, Wilson Audio, Magico, Cessaro or Living Voice they’d cost a downright fortune with their expensive veneering, lacquers and overall material wealth. But, who needs that other than the über-wealthy wanting to flaunt their investment? Go DIY, and that entails having others build the cabinets, and it’ll cost a fraction while, dare I say, delivering equally where sonics goes.
It’s about dedication, common sense and letting size/physics have its way. That’s not a recipe for potential bankruptcy, but rather using money where it really and mostly matters to achieve the desired sonic goal.