Very best wishes for 2018, one and all.
OK, I have actual experience of the grand total of one record-cleaning machine (Moth - £400 as a very simply assembled kit, less as a used item) - and the choice about which one was made for me - it came up at an attractive price here on PFM.
Irrespective of what any advertising spiel may claim, what you can use to clean records is very limited - water, surfactant/detergent and iso-propyl alcohol is really about it in the real world. Don't get sucked into any debate about one or other surfactant being leagues better than another either...........................
RCM are also not the panacea for all snap, crackle and pop issues either. Records either come clean and (largely) free of noise rather easily, or not to any worthwhile degree at all.
So, if anyone wants to clean the occasional record, whether new or second-hand, pretty much any machine, even very careful hand-cleaning, will do the job if anything is going to. If you are lazy, like me, a cheap automated (or even hand-operated) machine will suffice. If you have stacks upon stacks of records to clean, as a one-off, look at hiring a more automated system.
Over £2K for a machine - you're having a giraffe, surely?
P.S. I have used Nagaoka sleeves going way back before I can remember (probably because I worked in the plastics industry for 17 years from leaving school and recorded music was unknown to my parents, and me, until quite a while after me leaving school), so I am making educated guesses, but record care and storage will be at least as important as cleaning all but the filthiest second-hand records.