Just last week I bought a new E8400 processor from Amazon. I was going to buy it from Newegg, but I heard that Amazon has a 30-day price guarantee: if the price falls within 30 days of shipment, they’ll refund you the difference. I didn’t think I’d use it but it was nice to have.
Well wouldn’t you know, the very day after I received the processor, the price fell by $10. I headed over to Amazon, filled out the Contact Us form, and that same day my credit card was credited the difference!
Many online retailers offer price guarantees, so if all else is equal, choose the store with the best guarantee.