To have health care on a voluntary basis, it's about 220zl a month.
Delph, I have already posted about this. I have been paying a voluntary contribution to ZUS for about 4 years. It started off at around 220 złoty but has risen over the years to present cost of around 360 złoty per month.
My partner has explained that they base the amount on the average Polish wage (which seems to be rising every month). For the first couple of years we paid at the post office as it was impossible to pay by standing order at the bank, due, to a fluctuation of a couple of PLN each month. The computerised version to allow you to pay over the internet will only allow you to do so "if" you have a "NIP" number, otherwise it will not work, so, even though I do not work I had to get one.
As is typical in Poland, you still have to fill in the ZUS form and send it in every month, even though they have a record of your online payment. I take it that this is necessary for someone in the office to have something to "stamp". NOTE: If you make one mistake on the form, they will send it back and make you do it again!!!! The penalty for doing this could be detention or writing out 100 lines.