How cheap can you go and still be happy with the sound?

@immatthewj ....and I will basically agree on some levels of the pursuit of the 1% (and narrowing) 'level of perfection achievable currently'...

Given ones' level of 'a proper space/venue' for ones' equipment, the qualities of the played media(s) with the choices of said equipment driven by taste and the depth of ones' credit/cash/or the contingencies of outright theft....Atypical for the bulk of A'gon associates for the latter, no doubt. ;)

Based upon what I've read here and elsewheres'. there would seem to exist almost a variant of an 'event horizon' in terms of the apparent responses of a given set of equipment in a given space occupied by a very special pair of ears that can apprehend what's being experienced..

It would appear that to experience this 'edge of the probable' one will need very deep pockets and a near degree of absolute silence over working towards and achieving this goal to some degree....

Owning ones' own manufacturing facility would be a plus; one that is very profitable to allow the research and the creation of the 'space to play within' ought to be in parallel with the former....

And then...keeping the lid on what you've done.

A Saudi prince would be the most likely suspect to do such.
One just has to be of that societal group to do so.....

I'm certainly not, so I'll just continue to wade through the sludge I tolerate....😏

I’m surprised that setup has not been a much larger part of this thread. It makes a huge difference in even the least expensive system. Make sure the speakers are wired in-phase, that each is exactly the same distance from your ears (like within a quarter inch) and ensure that the tweeters are at the same height above the floor as your ears when in your listening seat. You may well be amazed how good even a cheap all-in-one system can sound. 
 

In my experience of more than 50 years, setup is the most often overlooked part of entry-level audio systems. 

@gigabit, agreed on phase and phasing proper, which ought to be easy; one needs to ensure that any sub being run is in phase as well.  Any sub worth calling it one should have a switch to reverse such....

Tweeter heights should automatically be the same unless a disparate speaker array is underway.....odd to note, but I've not experienced everything in all circumstances, either...🤷‍♂️

The 1/4" distance comment is a bit daunting for any species to pull off, however.

My cats can do that, but I'm not so motionless.  I suspect I'm not alone at that, but can stand to be corrected....
If one has the cinderblock chair with a molded seat, back, and head restraint could make that work....straps optional, I hope....🤞

"The house is on fire!"

This Opus is nearly complete! I'll be outside in a moment!

Not-So-Famous Last Review/BBQ Division.....

Ive been upgrading my rigs over decades buying, selling for decades. From humble "hand me down" beginnings I have been through many different modestly priced set ups over the years, I enjoyed them. With each upgrade you realize the increase in performance, as your set up progresses in quality some upgrades have a bigger impact than others. There is a point of diminishing returns or a level at which upgrades do not make as big of an impact because you have reached a point of relatively good performance.

This point of "Good" performance will be different for each audiophiles journey but for me it came when i reached speaker performance of a certain level and that was a pair of old Ohm Walsh 2 (made in the 80's, I bought them in the 2010s) that i dropped off at Ohm to have restored. After hearing them at a friends house i knew i liked their overall character, Omni directional speakers are very life like. I ran my restored Walsh 2's with am inexpensive Denon home theater receiver and i was in heaven. After some time I ended up scoring an old Rotel Solid State integrated from the 90's and that when i hit "Good" performance, the veil was lifted, the bass was controlled the sound stage was wide and deep like ive never felt before in my own environment. Ive moved on from that set up but from that point each upgrade was enjoyable but did not have as big of am impact.

In short, you can have an enjoyable rig for less than $1,000 bucks.

Funny because I heard a blue tooth speaker that sounded  pretty freaking good and a pool party,.The thing only cost $37 bucks.