Here's a list of some of the places I've bought craft supplies!

The usual:
(Great for everything such as scrapbooking, cards, painting, knitting & crochet, material, jewellry making)

(Great for paper based craft and painting)

Pictures printed from the internet
Big W, K Mart and Target (cards and scrapbooking)
Basement Books (cards, gift wrap)
Typo (gift wrap and envelopes)
Go Lo (paper craft, kids craft, beads)
Hot Dollar (paper craft, kids craft, beads, embellishments)
... and other various discount variety shops
as well as:
Walmart [USA] (similar to Lincraft, Spotlight but smaller selection, also good for freezer paper)
Japan's 100-yen stores [or those $2.50 stores such as Maruyu lol] (cute papers, origami paper, accessories, paper tape, laces, material)
Hong Kong street markets (hole punches)

Craft expos
... such as Craft Expo and Stitches & Craft

Stampin' Up

There are also speciality craft stores and many places online such as EBay which stock items which are good for craft storage, a good place to search is in craft magazines which advertise many stockists.

Other than that I've also recycled materials such as backgrounds/colours from magazines, Avant postcards, wide length ribbon (that someone didn't need), leftovers from overhead projector sheets.