I've used JacksSmallEngines.com and ebay as well
I'd like to order from ereplacementparts.com (also a great site for looking up, they carry everything from lawn and garden equipment to power tools) but they need to figure out their shipping to Canada and Canada border towns.
I live close to the US border and order from online sites and ship there, to save on shipping and I declare through the border myself (saving courier fees from UPS and Fedex), but ereplacementparts still charges full Canadian Shipping and Duty when shipping to a US address from a Canadian Credit Card.