It is from the Samoan language (Samoa being an island in the Pacific..)
Most of Auckland, New Zealand is flooded with Samoans..lol
'Sole' means ..Boy.. it is used in an informal way of talking... often used by teenagers...
Boy in Samoan is formally known as a Kama..
Oi Sole Hows things...?
An Australian version of this type of greeting might be..
Hey Mate, What you been up to lately?
Prices shown in USD.