To answer your question is rather difficult, as it's all based on taxes and therefore a percentage of your earnings. So it could be $50 or $500 - at least for the UK system. Though over the recent governments it's become more and more blurred (as in where the taxes actually go to). However, removing that issue, going to see a doctor under the UK healthcare system would cost you no money "upfront". Going to the hospital for a broken leg would cost you no money "upfront" - as in you have already paid for it.
There is also one thing which isn't talked about allot lately and that is with the NHS you simply turn up, get your treatment and leave. There is no paperwork to fill out, no justification either. You need it, you get it. Though there are some situations (mainly with regards to new drugs) where you don't always get what you want. Want being the operative word.
Also remember that we (UK) don't get the medical adverts like the US. We get Over the Counter adverts, but anything which needs a prescription is never advertised to the general public - so we are reliant on the doctors and not advertisers.
There's also that peace of mind that if we need health care urgently, it's there. People complain about waiting times, and it's probably true, but for anything serious you get the support you need.
You asked about breaking your leg etc.... Well, here's my experience with the NHS.
Mother wakes up one morning, walks down the stairs, promptly collapses in a heap. Step-father calls emergency services (999). Ambulance arrives in less than 10 minutes time. She's at the hospital in less than 20 minutes time. It's determined that she has just suffered a burst brain aneurysm and given drugs for treatment. She is placed in a high intensity unit and watched over for two weeks.
She gets worse and is transferred to a specialised hospital for treatment. She lapses and goes into a coma and is placed into a unit where there are 4 patients and four (always in the room) nurses and two doctors. She exits the coma - of sorts. She is then in surgery for an operation (coil placed at the point of the burst) which is carried out by the surgeon who invented this procedure.
She remains in the same unit for another 2 weeks and then placed in a general unit for another month for observation. She is released afterwards but given 6 months care support for rehabilitation.
Cost? Nothing (except obviously for the taxes paid).
Peace of mind? Definitely.
Saved her life? Absolutely.
The NHS ain't perfect - no-one is saying it is. But having that safety net, no matter what situation you are in (either rich or poor) is something i would never want to have without.