Amazon.com. I'm addicted to them for books and collectables. I collect shotglasses... You never know what you can find on there for cheap. Then I enjoy going to o.co for clothes, home supplies, and other pieces. It seems to be a nice website.
I go to Amazon for just about everything. I usually compare prices first and Amazon seems to always have the best deal and I love the ease of returning things to them. For scrapbooking supplies I usually go to bluemoonscrapbooking.com - they have great prices and service. They usually call me to thank me for my online orders. Nice touch.
I use Amazon prime (got a year free because I'm a student) It saves me money on items and free shipping - woohoo! I plan to continue the prime membership because I feel it is definitely worth it. You can find just about anything on Amazon - usually much less expensive than in a store.
I also use eBay a lot too though for bulk or wholesale items - I did a lot when I was in business making crafts and whatnot.