We have one provided by the hospital and you just buy the pads. Which is fine as long as you dont have a quick labor. If you do you might get there and you are too far dilated and progressed for them to work effectively requiring other pain relief. I have heard they are only really effective in early labour.
But if i dont need to use them our hospital refunds the money.
Most of the time you would hire from physiotherapists or you could try a chemist. But it is machine used by physio's so maybe call a local one near you and see what they say - they sould be able to tell you where to get one anyhow kellied