Evening all,
I got my doppler from ebay (new) for maybe £25 including the gel stuff which makes listening better. Its called "Angel sounds" and looks like it might be a bit rubbish, but works really well, and has 2 earphone sockets so DH/DP can listen in too. Suitable from 10 weeks I think.
I got it at around 15 weeks during my last pg and was really good for those weeks before I felt regular movements. If i hadn't felt anything in the day, I would have a listen at bedtime, and although it might take a while, I found the HB every time.
I would say after about 25 weeks, I would rely on movements to tell me everything was OK, but it would be nice to listen in now and again and check HR wasn't too slow or fast.
So now is the time to get one if you are thinking about it. I figured £10 to hire one for a week or few weeks wasn't worth it when you can buy one, and can always sell it or lend it out to get more value from it.