I would never recommend ebay as there are way too many people who are there just to con you. Stick with a proper electronics site which provides warranty for their products. Just google what you need and you will get a list of the sites. Ebuyer is a good site. DOn't know if play.com operates there(pretty sure thet they do!) try them as well, free delivery and good service, quite cheap, just not that much choice of parts. Have a look around, you ll find loads
Don't recommend Ebay for sensitive or expensive parts, but for fans, HSs, cables, etc I would say you would be fine, just read the statement before you commit to buy. Newegg is good, but...try slickdeals.com, you may find what you need cheaper and from a reputable store (often available in store to save shipping). Also, for small stuff local may be the way to go due to high shipping rates. Best Regards, Mav.