Have a read of our guide to healthcare in the Czech Republic for a start. It's compulsory to have health insurance as a resident of the Czech Republic, and as an expat, your worst case scenario will probably be having to pay for this yourself.
Will you be working there before retiring? Expats who are employed by Czech employers automatically have access to free healthcare because they'll contribute to the national healthcare scheme.
There are many sites where you can compare the cost of living with your own city. Numbeo has a tool specifically for healthcare.
Hope this helps,