I also want to try electroetching.
Super easy to do. All you need is some saltwater (or salt vinegar) solution (the saltier the better), a DC power supply (as simple as a 9V battery) and some gator clips with some type of material to soak up the solution to conduct the current through to the steel.
I made a rig using a 12VDC AC adapter (AC to DC) with a 500mA current limit. Basically a wall charger for a electric shaver or cell phone. Hit up a 2nd hand store like Goodwill or a garage sale and you can get one for cheap or just search through your junk to find one you're not using (everybody has one stashed somewhere!). Cut off the barrel plug and strip the wires, attaching gator clips to them (you can get them in the "Odds and Ends" of the hardware section at Lowes or Home Depot).
Here's my set up (when I etched my ZK Famine):
White is negative (attached to the steel as the ground), yellow is positive (which would have the etchant soaked pad of cotton or similar material).
Using the higher voltage/current limit makes the reaction happen faster. Really sizzles and blackens the cotton Q-tips or scraps of rag quick. It will get hot but not enough to start a fire because if the "etching pad" dries out, it won't conduct any more. DC etching is MUCH safer than AC. Using AC (to blacken) is okay as long as everything is well insulated. Forgetting to make sure you've properly insulated your set up will be like sticking a fork in an outlet: Not a pleasant experience.

Before I tried it on any knives, I etched a keychain fob I've got that had a vinyl sticker applied (Go Ducks!) and it worked really well.
Also (as an experiment), decided to do a bunch of etching on my "freebie" ZK Acheron knife and used simple fingernail polish as the etchant mask:
Good luck with whatever you decide to do...!