I'm in the market for a stethoscope

I'm currently working as a tech and will be starting nursing school (RN) next year. I was going to wait to purchase my first stethoscope until I started school, but there are too many instances where I need to conduct a manual BP at work and I have to hunt down someone with a higher quality stethoscope because I can't hear on those $5 plastic ones we have laying around.

My only main requirement is that it'll fit in my ears. I have really small ears and I have yet to find earbud headphones that work for me - even when I switch to the size small. The main reason I have problems hearing on a stethoscope is because the earpieces don't fit into my ears correctly. I'm wanting to buy something fairly nice, but my maximum is probably $150 or so. My mom is going to buy it through her work so it will be discounted.

I currently work on a med/surg floor (surgical primary, oncology, medical secondary). I eventually plan to work in acute care (trauma, ICU, ED, etc).

I've heard good things about the Littmann Cardiology III and Master Cardiology, but I really have no idea. I just figured if I bought a high quality stethoscope, it might make it easier to hear sounds without it fitting well into my ears. Any suggestions for a nice stethoscope that will work for my job as a tech, in nursing school, and as an RN would be greatly appreciated. Also, if anyone knows where to get XXXS earpieces, that'd be much appreciated!