So I use Master classic 2 stethoscope and it’s really good. I am very happy with it. I know it’s above what you wanted to spend, but it’s really worth it spending money on an adequate piece of equipment. This one has a variable pressure diaphragm so you can hear different sounds without flipping the bell. I compared it to a more expensive model to see if I should upgrade, and didn’t hear much difference. So decided to stick with what I have. Maybe you can find a used one on eBay.