We just got a cheap one at Walmart that came with headphones. I think it said you could hear as early as 17 weeks and at 20 weeks we couldn't hear it. My husband would occasionally say he did, but it wasn't enough to tell.
An expensive one may be able to pick it up better.
I'd encourage you to do some research on Doppler and ultrasound technology and safety before using them.
Personally I don't think they have been proven safe so these links are admittedly biased.
Searches on www.google.com will show dozens of sites so you can research this more and see both sides.
I bought a fetoscope. http://www.1cascade.com/display/Fetoscopes/ From about twenty weeks on I could find his heartbeat anytime. I loved hearing it. We did use the Doppler a few times during labor to check on the baby. There was no way I could lay on my back for the fetoscope to work!
Anyway, I hope that helps in some way. Good luck finding the right choice for you.
And congratulations!!! I am 45 and just tested + on an HPT yesterday. Just when I was beginning to think that I was too old to conceive!
Wishing you a healthy pregnancy and easy delivery!
The truest answer to violence is love. The truest answer to death is life. The only prevention for violence is for the heart to have no violence within it. We cannot prevent evil through any system devised by mankind. But we can grapple with evil and defeat it, but only with love—real love.
It is possible to rent Dopplers for a few months...when pg w/ my 1st, there were mamas on a different BB that had a link to an online resource that would rent the Doptones, as they cost around $400.
My hubby would hold his ear against my belly and could hear the heartbeat that way (midwives, being professionals, use the fetoscope, LOL......but you CAN hear it with the naked ear, provided your EAR is in the right place and you know where to pick up the heartbeat [varies w/ babe's position in womb.])