Check out www.simplecare.com . This is an organization of "cash only" providers, mostly physician offices,few if any hospitals.

Look into HSAs (Health Savings Accounts) http://en.wikipedia.org/wiki/Health_savings_account.

Cash discounts vary by location, but should be more than 15%,
sometimes as much as 50% (just like any transaction, charges are negotiable, don't take the first offer, also "shop around" if time and circumstances allow.