Dell also sells 200$ computers that aren't worth more then 100$ If customers are willing to know that they will get there moneys worth even without Full customer support then I think that would be ok, I would buy a Really cheap high end computer that on dell would be around 5-6k and alienware around the same and have it on my site for around 2-4k. But I have weekends open to me so I could setup a system where Customer support can only be reached on weekends. Small price to pay for a nice cheap high end computer or what not that they have. ^ That's all till I can get Full customer support. Which will be till I get out of college.
So essentially, you're limiting your demographic to gamers, which, as a whole tend to know that Dell overcharge, and are much much more likely to buy from somewhere like newegg and use a PC builder option, in which case they're still much cheaper than you're offering. Of course, you don't offer any form of real support (a kid on the end of a phone on weekends is not technical support). Are you a certified systems engineer? I don't think so. Therefore no one in the market for a cheap home office PC will give you a second glance. You've gotten a poor idea into your head, and are using optimistic estimations to make you think you're gonna get rich.
Well, we've pretty much all been there before, and had the same thoughts, but realistically it takes considerable investment and work in order to actually make money from it.
Dell sells $300 computers that are "worth" 350. the fact is that in the industry after all things are considered margins are very small and any profits are made via tremendous volume. IMO you'de be best off to focus on the mid-highend and NOT the value bin, lesser need for backup.
conversely, if you're knowlegeable and able to troubleshoot on your own stuff you can RMA and be back up within 3 days - I have. that's why any work I do is for friends locally and at minimal profit, usually only around 5%.