As with everyone else, AmigaKit and Vesalia are the two I would highly recommend. I've ordered many items from both stores and they have both always been fast and efficient and I've never had any problems.

Ebay can be a bit hit and miss, but as long as you are careful and do some research into what you want to buy, and make sure the item being sold is exactly as you want then you shouldn't have any problems. It is however a good idea to only buy from sellers with a very good reputation and a feedback over 100.