Niagara Cycle for tires and tubes since they have a very large selection at decent prices. eBay for everything else. I just received word that Niagara Cycle had shipped my tire order when I found out I needed a couple of 184mm spokes. Too late to add them to the order that included $10 for shipping. The spoke price at Niagara Cycle was good (34 cents) but the $10 shipping charge was a killer so I ordered them from an international seller with free shipping on eBay. eBay makes it easy to find the lowest price seller while Amazon does not so I no longer bother with Amazon.