It's bound to be one of those things that will vary from person to person... it's not a magic remedy, but for me it makes a real difference. My OH went out and got me one as I was in tears one evening with awful pain, tried it and it made a significant difference.
I now wear mine throughout the day when the pain is the worst and in an attempt to keep off the heavy painkillers.
It creates an electrical impulse that confuses the nerves that send the pain signals (which are also essentially electrical impulses) to the brain, it's a similar technology that slender tone belts work on, funnily enough, so it's quite safe. My unit was around £50-60.
The pads wear out after a while (lose stickiness) and need replacing, they cost £12 for two new sets of pads.
For the cost of a haircut & colour, it may be worth a try?