I bought for three reasons:
1. cause it ended up being around the same price as to rent, and the difference in quality only amounted to about a 1 week lag
2. I know that we will be trying for more kids some day...
I got a HiBebe - I think it was less than $100 from ebay...
I could hear baby at 12 weeks/barely...but I have a very retroverted uterus, so my OB said it would have been earlier if not for that (I think the average with that one is around 10 weeks)...
It does display the heartrate on the monitor...
Oh, and now, baby HATES it, every single time I uses it, he kicks it, which I personally find to be amusing to no end!!