How much you want to pay depends on the value of the data you want to recover.
There are free software out there - and some may be very good. And some costly software may be poor.
If you are brave, google:
free data recovery
I would follow the recomendations posted if you are not sure!
Just remember - there is not much room for error - read the instructions very carefully. Reading the manual before you start would be a very good idea. And be patient. It may take some time.