Papa Moomin is pennywise. 
I went over budget with it anyway. A RAID stack is not cheap if it's done properly.
No, it's not, but, right now, we have 2TB internals in our store from Seagate for $139. They are standard types (7200 RPM, 6ms seek times), but in an array, paralleled, they would probably be fine. Dunno, though - Haven't tried it.
Had I not spent my monthly budget on all those externals, I would probably grab a couple. I really NEEDED those back up drives though.
(I can now get rid of about seven 300GB drives where everything is backed up - or NOT. I can never delete music ...

)