Well quoting a poorly regulated, low efficiency (70% ouch that is going to hurt power costs) junk PSU, unknown radiator as a substitute for complete sealed waterloop, and "all fans = $0.60" doesn't help your case.  Lets ignore the fact that the site you linked to is notorious for bad prices.  Ask for a firm quote and see how the prices magically change.

Still lets use your imaginary parts:
Junk PSU: 4*10 = $40
Imaginary complete sealed watercooling system: 3 * $20 = $60 (w/ pump, radiator, lines, waterblock, shipped ready to install yeah right.  you pointed out a radiator is $12.  Show me where you can get a pump, reservoir, tubing, connectors, copper waterblock, and assembly for $8 more).
Case: $6 (you don't really believe the listed price on alibaba do you.  Ever asked for quote on a specific model?  Suddenly the $10 special disapears marked up 300% or more)
Fans: 8*$1 ea (its 8 not 2 2 per radiator plus 2 exhaust)

So just these 4 junk components puts you at $74.  A $50 per TH/s target gives you only $60 for an entire system.  Your already overbudget with just the non-electronic components. There is still the ASICs, minor pcb components, pcb manufacturing, pcb assembly, major assembly, and testing.  This also assumes 100% yield, no fixed costs, overhead, taxes, salaries, etc.

Like I said my guestimate of $1000 per system was just a start.  I even said you likely can cut that by 50%.  That is a huge difference from saying you can cut it >95%+ to meet some silly 650 PH/s estimate.

Thanks by your own junk part links you just disproved $50 per TH/s nonsense.  You know it and I know it you just can't admit how utterly silly your projection is.   If you can't source the basic non electronic components (power, case/frame/rack, cooling) for $50 per TH/s it is utterly pointless to show that as a projection.  Moore's law isn't going to make a PSU or case or fan drop 50% in price this year.