There is no way on earth I would (a) take time to switch out the heads of the stethoscope or (b) not lose the spares.
I'm a stethoscope minimalist. If we went a step further with your lover analogy, I'd be all the way to asexual. It's not that I don't use them, it's just that I'm not picky at all. Any random stethoscope is perfect.
I like to use quality equipment.
Most of my life revolves around my professional pursuits and at some level, good equipment makes the job more enjoyable. (rather it eliminates potential frustration)
I switch out the heads between jobs, not between patients. I was using a master cardio for years (I got it at a liquidation sale for 50% off) but the giant bell in a neonatal ICU was not working out at all.
To change out the bell it takes about a second, it just snaps in and out.
I like it much better than having to have an adult stethoscope for cardio surg and a seperate stethoscope for neonatal.
Many of the incubators have scopes attached, but for the kids not in an incubator, finding one of the community ones can be very time consuming.
I don't think new or occasional providers should go out and spend lots of money on stethoscopes. About $75 seems about right.
Like I have said many times, quality equipment does not amplify the skill of a poor or mediocre user. It simply allows a highly skilled user to not be inhibited by the equipment.
You could have the best bicycle ever built, but it will not help you win the Tour de France if you are a recreational rider.