Hi L-S
We actually have an entire category of ElectroStim toys which you can browse here.
All e-stim toys should be used below the waist. Yes it is a safety warning: I don't know why you say "just" a "safety warning" as if that means it doesn't mean anything?
Yes, it is a safety warning and the reason for it is because to use an e-stim unit above the waist/across the chest/near the face is extremely dangerous.
You can learn more about Electro play in our Buyer's Guides here.
I hope you'll take the safety warning which says "not for use near water" more seriously?
I would add also that whilst I understand your disinterest in paying a lot of money for something you're not sure if you'll like, E-Stim is classified as "serious sex play" as it carries more risks than other erotic exploration, particularly if used incorrectly.
When it comes to riskier sex play, always invest in the best quality pproduct you can reasonably afford. Can't afford the fancy one right away? Save up.
It's better to wait an extra month and save up for a decent toy, than rush and get a cheap toy that won't feel as good / has fewer safety features.
Happy exploring!