For people that buy their own parts and build their own boards, you normally do price searches on digi-key which is dramatically overpriced. I've forgiven them for this because they're convenient and they cater to individuals/hobbyists so I figure their handling costs are higher. But lately, I've been liking the chip price search engines and thought I'd share two of them that I use a lot:
Findchips - Findchips does a search over many distributors (mostly US based) including the big ones for the hobbyists (Digi-Key, Jameco, Mouser...). They have a decent interface and show which distributors have the part you're looking for as well as the price.
Octopart - I just found this one recently. It has a search engine and also a category tree that you can use to look for stuff that you might not know to search for. It's still quite a new site and many of the categories are empty (similar to my site?). Also, Digi-Key is currently suing them to take their prices off of the site, although I don't know why they'd turn down extra traffic and sales. It's a good site though and when you do searches, they even search the semiconductor manufacturers for the price listings. You can test this out by doing a search for CC2420. Note: Manufacturers should help them build up their product category trees by listing their own products. It couldn't hurt sales and might even improve it.
Anyways, I just thought I would share those with everyone because they're quite useful.