i think the item in ur link is a blank key, without the keyless entry tingy (not sure what its called exactly!)
last i checked, LSM quoted me 1500 to replace my key, cuz the cover for the keyless entry button thing inside was broken....
so my key is held together with some tape currently...
as for relacements...
the only option i can think of is to carry ur spare at RUDD, on duke street, POS.
they do "chip" keys for 1200
i am currently looking for a blank to insert my keyless entry thing but they are £28 on ebay, last i checked, and i spoke to a lock smith who said he wont risk cuttng the blank key on his machine as he is unsure of the material and doesnt want to risk damaging his machine!
i think you should give RUDD a call and find out the option for having the key programmed! etc.
an update us!