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

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.

A couple of reviewers talking about high-end gear that sounded lousy and budget gear that sounded better.

All that glitters ain't gold