Personally, I could care less about the cost (but it does bother me). IO should have mentioned above that in nearly all cases, urgent care is more appropriate (my provider has one open during daytime hours).
Also depends on your insurance provider (at least in the US). Previous insurance I had wouldn't cover urgent care clinics, but would cover ERs. Stupid beyond belief, but it was a small company so I guess there were compromises on the plan. Luckily I no longer have that plan and have a much more sensible and comprehensive plan.