I've noticed the same in different mags I subscribe to. There are some differences in the pricing scemes.
I have spent about 10 grand on systems I've built for customers in the past year from iBuyPower. Don't let the site fool you, you can order the parts and do the builds yourself if you so choose.
Here's my take on iBuyPower.
The prices are hard to beat when configuring a system. They have a pretty decent choice of components, inventory is always stocked (I've never had to wait for a backorder part). Shipping is average.
A order I placed in January got messed up and they sent the wong motherboard, hard drive and video card. I called for an RMA and the parts were overnighted

- I still had to ship the other parts back but they paid the shipping.
My suggestion is that if you do order, call the order in and ask for Gordon - he's efficient and knowledgeable.
I recommend iBuyPower highly and that's a whole lot coming from me - I can be extemely demanding when I spend that kind of money

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Mike