Which external HD can I add to my Bolt, now that WD does no longer...

Which external HD can I add to my Bolt, now that WD does no longer makes the DVR expander HD's with eSata. They now only make USB 3 external drives. The few HD DVR Expander drives for sale are all $300 and over for a mere 1TB.

Can I use an internal drive in a case with eSata?

Which external HD can I add to my Bolt, now that WD does no longer...