Something to consider:
Do you think people will arrive at your site simply by typing it into the url bar? Have you heard of newegg.com? They appear to be doing quite well, and I doubt more than a handful of people arrived at their site by simply typing "www.newegg.com" the first time they went there (assuming they hadn't heard of it of course). So I don't think focusing on a great .com name should be a big deal. You could even go with a .biz or whatever's cheap. Just get good advertising, get a good strong reputation, and you could call it murkysaladentree.com and people would probably have no problem buying a computer from you!