You are handy, and if you have tool and brain to build that skimmer then small cleaner is few hour project top and in parts cost you closer to 20$ not 200, engine and oil seal are most expensive parts(and timer).
I mean, i do not care, i do not sale them so for me is all the same will people have them or not, but neck cleaner is upgrade, not miracle tool what produce snake oil, it alow you to keep skimming at max all the time and also alow you to not clean it for long periods of time. If we look how fast gunk create with dry skimmate to call it same a cleaning interval would be a 2 or 3 times a week not 1, and often it takes hours for bacteria and sludge to cover wall (or whatever happen) and to skimm at full power again. Beside, i do not know anyone who have a reef tank for years and do all maintence on time all the time ...
Many gadets we do 'not need', auto feeders, dosing pump, etc, but they have their place and is not useless