Taking a degree online in some cases will cost you even 80% less than taking the same class in traditional way. .
To give you an idea an associates degree with a semester hour costing around 60$ (there are many comm. colleges than offer such rates) would cost you 3600$.
If you’d like to attend a John Hopkins at 900$ per semester hour a master degree would cost you ( 36 hours) 32,000$.
Usually you can expect prices ranging (in country) from 250$ to 350$ per semester hours witch translates into a bachelors degree costing anywhere from 30,000$ to 40,000$.
As you see it entirely depends on what school and program you want to attend and you should always simply get that (free) information from the school itself.
You can browse available online degree programs in top menu and see all online colleges here.