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

Love this prompt- I feel like an aardvark here. Instead of having one system I try to perfect, throwing all my resources at it, I have several that explore different approaches based on where I live, work, and what mood I'm in. I don't like buying new- I find there's no joy in unboxing. Experimenting with vintage gear is more fun- I learn a lot more about engineer's creativity over the years that way. At home, in my living room, it's all about vinyl, Quad ESL's and their small, incredible sweetspot. This is not a budget system, in terms of time, money and effort. And it's rewarding, even as it encourages listening to the the system as much as to the music. But now, at my cabin in the woods over the summer, I recently went the other direction in an extreme way- Bose 901 IV's ($300) and an old Creek amp ($100), hooked up to an ipod, and a thrift-store Phillips belt-drive ($10) and Audio Technica cartridge ($50). The system is on a screen porch, but with a very reflective short wall of wood behind the speakers that enables the direct-reflecting principle of the 901's to work. My taste out here runs more to dub and other rhythmically propulsive genres, and I find that despite the Creek's low output this system really rocks out, and the extreme sense of space that's a "special effect" of these speakers is a ton of fun with the music I want to hear out here. Plus, it sounds like it should anywhere in - or out!- of the room. Depending on who you are, there is a lot of happiness possible below $500 . . .

An old cheap setup I had, (not pictured is BS Node2i) Enjoyable? Yes. High Quality sound? No.

i have a basement system consisting of polk model 10s ($200), an integra dtm 5.3 receiver ($100) and an integra dps 5.5 cdp ($50ish), and recently added a wiim mini streamer ($60)--all prices used. sounds excellent. i also have a garage system consisting of jbl hls 610s (great budget speaker), a sherwood rx4100 receiver (remarkably clean-sounding cheapo) and an integra cdc 3.4 changer, all of which totaled  <$150. also sounds purty darn good. i also have some kilobuck gear, but i often find it somehow more rewarding to put together the uber-budget stuff.

I can be happy listening to the radio in my car. When I mow the lawn, I wear some $27 ear buds Bluetoothed to my phone and I’m happy. I have an old boombox in the garage and it makes me happy.  I have some ancient Yamaha two-way speakers plugged into an equally ancient receiver that’s plugged into the Sound card on my computer And it makes me happy.  I have a newer boombox that goes outside when we’re out there entertaining and it makes me happy.

I also have a rig inside that I listen to most of the time and it makes me happy.

 try to keep music in my life as much as I can, because IT makes me happy!

Let's not be ridiculous. Good sound has a cost and it should. I don't think there is anything under $10k-$15k that would qualify.

And we wonder why the word "audiophile" has a pejorative connotation. This is just a tad elitist. One can "love audio" at any price point...there is no minimum buy-in to the club.

To answer the OP,. I've bought audio gear for my kids, and listened to various (factory) car stereos, and thought the sounds was "pretty good" and enjoyable.  Happy to have something to listen to, enjoyed plenty. 

That said, I still have issues when someone puts on satellite music - the compression is so clear.  Not as bad with MP3s streaming at reasonable quality - 320 kbps.

My higher end stuff is more fun to tweak and play with, but I think basic music enjoyment can be had with any gear where some quality effort is made by the mfr.