Yeah Richard Nagy is pretty much the gold standard for this kind of thing. I've considered the pros and cons of doing this as well and I don't really see it as being a realistic option if your goal is to make money.
I assume you looking at purchasing, modding, and then re-selling netbooks? That is your best bet for keeping costs down, and should something go terribly wrong it's a little less devastating. But the other option of course is to mod and re-sell legitimate laptops but that's going to run you in and around a thousand dollars a pop, even more if you want to do macs, right? You end up being pretty heavily invested right off the bat unless you have an in with someone who can hook you up for cheap.
It's a tough call, once you factor in parts and labour, you start to have to charge a pretty serious amount to justify your costs, especially if you are 'in it for the money'. ;P
I think it can be done, because I am eternal optimist, but there are some pretty serious challenges to undertaking this kind of mod work, with end capital in mind.
Nothing wagered, nothing gained but you don't want to end up paying yourself out $2.00 an hour because no one wants to pay $3000 for a $1000 laptop. Regardless of how many gears you stick on it

When modding a laptop, for the most part, you're making it larger and more cumbersome that it is already, as laptops are pretty minimalist. It's almost easier to target the PC market as people expect something big and clunky, plus you have way more opportunity for mods whereas with a laptop, unless you rock some Datamancer engineering skills, you're kind of limited with your options.
Know what I mean? Tough call. I'm not shooting down your idea by any stretch, but there are a lot of factors to consider here if you are doing it with the hopes of turning a profit.