You can get a free app for the iPhone called unborn heart I am 15 weeks + and got a heart beat the other day I have ha the app for 2 months waiting if you don't have an iPhone maybe just look for other apps
I really want to get one I love listening to my daughter's heart beat
I've decided not to.get one because it would just cause more worry
I got the Sonoline B fetal doppler on eBay for $45 and it works great! I've been using it since I was 9 weeks and got a heartbeat right away
I got mine on ebay for $20 :)