where are you located? I’m familiar with several places that DO have credible machines you can buy used, but I have more local information that I have for other places (so…canada).
You’re correct to question the functionality of a used machine. That said, if you poke around here , you’ll find directions on how to do an egg white test or bubble test to ensure what you are buying is operable BEFORE you put your money down. I ROUTINELY find working epilators for $400- $1000 CDN , and if you are modifying things, you can easily spend this much money just purchasing needle cords or ports.
Some epilators ( the instantron for instance) use other standard type interfaces lie BNC connectors, these used to be used for thicknet ethernet and are now perfectly functuonal as epilator channels, so you may be barking up the wrong tree, instead of a banana port maybe you could use a BNC connector on your device and buy an off the shelf instantron cord… But all of this adds up, and yes , you can spend as much as it would have cost to buy a used professional machine on just parts and pieces to make a one touch work properly and it STILL will only be capable of galvanic, and it will still , do a very poor job of it.
James walker ( former moderator of hairtell) was one of the first people to drill this into my brain years ago. Often, it’s cheaper and will get you further along, buy jut going with a professional grade unit.
Believe it or not , I DO understand the limited budget involved in such projects, in fact, many will tell you when I first started I had almost no money, but on James advice, purchased a good used epliator and removed all my hair with it.I’ve never once regretted following that advice.
Example:
https://www.kijiji.ca/v-sante-besoins-speciaux/ville-de-quebec/appareil-d-epilation-a-l-electricite-electrolyse/1504285037
https://www.kijiji.ca/v-sante-besoins-speciaux/ville-de-quebec/electrolyse-apilus-junior/1499988737
side note: If you decide to go through either of these adds, probeholder/needle cords are the achilles heel of used apilus epilators, and i just happen to have several functional used cords and one brand new in the package for these model epilators I’d happily send out in the mail for $0. Such could also have their connectors cut off and a banana plug wired in it’s place I suppose, but I still dont recommend it as an avenue you should persue.