Nan... get a bus up to Dobbies Loan, and there is a big Chinese supermarket up there. I was only there last week, but can't remember the name of it, unfortunately.
Also, closer to home there is an Asian shop in either Park Street or Bank Street, right off Great Western Road... lots of cheap spices in there. Once again, I cant remember the name but it's something like RKK or PKK.
And as someone mentioned Whole Foods, there's one in Giffnock... a 38 bus will get you down there from the city centre.