Fetal Heart Dopplers?

Does anyone have one? What brand? How much? Easy to use? Just looking for some reviews on them. I'm dying to hear the babies heart beat. I'm 9 weeks today, and just getting anxious. My first appointment is Wednesday, but I just want the ability to be able to hear my babies heart beat whenever. I had miscarriage in May, so I'm just on edge this pregnancy! Any input is welcomed! Thanks!!