As I sip my $0.28 per coffee pod and read this thread, there has to be either a happy medium, or some diminishing returns on investment at some point.
Believe me, I know there is a science to anything - you can fall down a rabbit hole easily from everything to pistols, flashlights, coffee, etc.
So I need to ask the OP the subtle differences between the 4k machine, maybe the $500 machine, and the lowly french press.
What do you get for the extra $?
I'd love to give you a comprehensive answer but I'm not an expert and have never owned one, so these advantages are just my best guess.
Access. Double boiler setups give you immediate access to water at the temperatures you set for espresso and steam.
Control. You set the temperature. You control the duration of the extraction. My machine of choice lets you control and vary the pressure of the extraction. This all adds up to handling any bean, since different beans have different requirements. Light roasts, for instance, need a longer pre-soak and a longer extraction, as well as an extra degree or two of heat. Dark roasts will give up their goods more quickly and at a lower temperature, and would be too bitter with the light roast settings.
The machine I'm considering is actually low-mid price in domestic double boiler world. I'm interested in that world only because I don't want to yearn for an upgrade later. Sometimes I'm a cheap bastard but other times I'm content to buy once cry once. I'm going to use it every day so figure I'll go for The Tits.
But yeah, the coffee rabbit hole brings out the autist in me.