Robin Hood: The Complete Series is on sale today only for $41.99 on Amazon. (Royal Wedding Week means BBC set deals in the Gold Box all week.) It's a good price for the first two seasons although I recommend completely ignoring the last season (3rd). This show was the opposite of Merlin which had its best season so far in its third. It's light and silly and fun but it is Robin Hood and we had fun with it until they killed off Marian and made the third season unwatchable. It's no surprise it didn't get a 4th season.
I really, really hope the producers of Merlin have learned from the mistakes of Robin Hood. Both of these series are along the lines of family entertainment like Doctor Who, some scariness and such, but overall clean and suitable for perhaps 8 and older. Actually, I think the Doctor is often the spookiest with the strange aliens walking around in our world. Merlin and Robin Hood are historical fantasy and have an element of disassociation with them accordingly.