Parts and service can only be obtained through Epson, via their service partner DecisionOne. You call the Espon Service 800 number, give them the serial number of the printer, and tell them what's wrong. They will dispatch parts and technician to do the repairs onsite, usually in a day or two.
You'll need two heads, capping stations, ink lines, ink cartridges, drain lines, filters, wipers, and a few other assorted parts to be replaced. Based on my experience, this will run somewhere from $3000-6000 depending on exactly how many parts end up getting replaced and how long it takes. Even at the upper end you'll still end up with a great printer at an extremely low price.