@David
They're on Apple's online store.
Power supply:
http://store.apple.com/Apple/WebObjects/ukstore.woa/wa/RSLID?mco=MjA1NTgx&fnode=home/shop_mac/mac_accessories/power&nplm=MB283
Ethernet and monitor cables:
http://store.apple.com/Apple/WebObjects/ukstore.woa/wa/RSLID?nnmm=browse&mco=MjM1NjI&node=home/shop_mac/mac_accessories/cables