Thanks to the thoughtful discussion in this post, I have found an answer to my original question.
I consider an amp high end when it isn't some DIY trash, complete with crappy flimsy aluminum case and raggedy P2P wiring, with random small fires breaking out in the shitty power source, and RCA connections that spin like tops when you flick them, and to top it all off the DIY'er charges you more than cost of parts, probably to pay for the xanax script he needs to enhance his daily dose of methadone from the clinic.