***MAJOR SPOILERS*** The Main quest(help)

[Masa]

I gave the Mysterium Xarxes book to Martin and now he wants me to fetch a daedric artifact for him.
Well I have Azura's Star but I really don't want to give that away, so can I give him some other daedric artifact with less value and where could I get one?

[Cailan]

there are 15 daedric shrines dotted around the world.. theres a map of them at : http://img89.imageshack.us/img89/478/shrines6xn.jpg