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

My office setup consists of an AudioQuest Dragonfly Red, an iMac, and Definitive Technology Incline Speakers.  I like enjoy the sound using a variety of sources.

None of my setups are expensive.  For me it is all about the music.

I can & do enjoy good music on anything I hear it on. What’s really interesting is that the nuance & details I’ve come to notice & appreciate on the good systems I’ve had over the years get somehow imprinted in my brain & I seem to sort of fill them in when listening in my car or at my business but probably aren’t truly there. 
 

Maybe part of it is that we see what we want to see & hear what we want to hear??
 

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.