J.C.
Hi I.,
Congratulations on your pregnancy. I had also had a couple miscarriages before my first one was born. I went through Stork Radio. You can buy or rent. I rented and the doppler was brand new. It came with gel. Never had a problem and if you do, you just call and they'll replace it. I sent it back after I was almost ready to deliver. The whole process was painless.
The doppler is a good thing because it can give you peace of mind but it's a bad thing if you can't find the heartbeat and you freak out. When all that happened was that the baby moved. I used it less once I could feel the baby moving.
Good luck and try and enjoy your pregnancy.