If you have insurance, get your doc to rx a script
. They may pay for it, and the electrodes. My pain doc did that for me, and they paid.
I never looked on line, don't really know what is out there, sorry.
Most of them have different settings, or feelings. A steady tingle, or like tiny hammers are beating on you, and then there are settings I don't know what they are for.
Do you see a PT? Maybe they could help too.