There is an unfortunate thing in science and marketing.
The marketing department comes up with a name that will sell, and later, the scientists who actually build a thing that delivers what the marketing department oversold are left to ask the question, “Now what do we call the thing that really does what that other thing overpromised, but did not deliver, now that the name for what this does, is taken by that impostor?” (for example, Speed Control and Cruise Control, When one car company gave the name Speed control to a throttle set device, which kept the engine at a certain level, it did not stabilize your speed, unless you were driving on a flat track. Cruise control was true speed control that adjusted the engine throttle to keep the speed constant even if you went up a hill, or down a hill, but could not use the name that best described it.)
As confusing as it is, the word Epilate means to remove, an Epilation is a removal, and an Epilator is anything that removes. As used in the USA, this is always referring to hair removal though strictly speaking it could be removal of ANYTHING.
Now, a REAL professional electrolysis machine, as it is named by scientists, is given the name “Electrolysis Epilator” or “Electrolysis Epilation Machine” The cheap things that rip hair out by the roots, are marketed as “Epilators” and since they DO remove hairs, they are justified in using the term, as they do remove something. The problem is that the name doesn’t make the distinction between permanent removal, and temporary ripping. Making it even more confusing, some companies call their professional electrolysis machines “Depilators” or “Depilatories”, which serves to confuse them with the chemical potions what seek to chem-burn your skin and hair to effect some level of removal of surface hair.
It is because of this confusion, that this string that you were directed to was suggested.
The problem with the cheap battery operated things you have seen is that they are made to make money off people who buy them and then toss them away in frustration. Those devices are not made with any thought towards what one needs from the machine if actual use for long term requires. You need something that will be easy to handle, and maneuver, while having a stable power source, delivering a steady and duplicatable current output.
You can only get these from a well made machine, and things like the Vector are not well made.
Over and above this, the better the machine, the more fogiving it is of the limitations of the skill level of the user. A professional could make do with a primitive rudimentary device but a novice would just make many costly mistakes.
Most people who buy those cheapoes, burn themselves once, and toss them into a drawer, never to be seen again.