I have a sonoline B and LOVE it! It cost me $40 off the internet best 40 i ever spent!
I have one, its great had it since 10weeks and now being further along its great for ease of mind when movments arent happening .. angelsound make a really good one at a reasonable price
Yes, they work! Might take a min to find the position of the heart, and you have to be at least 10 weeks but they do work :-)