Anything that reads the DOM/CSS will be able to make it human readable again. Especially Firebug and Chrome's Inspector. You could even leave the source minified and add your custom CSS cascades at the bottom of the source that you take from Firebug.
Seems like something that just punishes people who'd buy it in the first place like most anti-piracy schemes.
If it becomes a problem for you and you think there are people who would steal them without that but pay you with then go for it. But it will make it harder to evaluate themes for people who do actually want to buy them.
This is an awesome idea by the way. I love the choice on Theme Forest but I the flexibility of Bootstrap is brilliant too. I'm also using Bootstrap whenever I prototype anything and being able to just buy and use a theme later on would be incredibly useful (obviously it's not quite that simple, but it could be close). I will almost certainly be buying lots of themes from you assuming you get designs (which I'm sure you will!).
I'm surprised ThemeForest don't have a Bootstrap section yet actually...
You could perhaps partially obfuscate the code. But it'd probably be tricky to ensure that at least some interesting parts remain untouched. Perhaps let the template author markup those areas?
Meh. I'd say don't bother to obfuscate it. There's a real cost, and no obvious benefit (anyone making a real site would be stupid to steal their theme; anyone interested in stealing would just steal from a theme purchaser's site instead of you if you obfuscated).
From a dev's POV - I won't believe you on the elegance & quality of the source unless I can see it, and that's very much what I'd be interested in paying for (an elegant/clean/flexible UI base). Obfuscating at all is somewhat like selling a fabulous custom car but hauling a dirty tarp over it before letting the prospective buyer get a closer look.
Besides, it's HTML & CSS. De-obfuscating (unless it's seriously mangled, which seems dangerous) is as easy as copying the DOM and composed CSS from Firebug, I imagine, or cut/pasting the files into a good editor and auto-formatting.
Or something; I can't say I've ever de-obfuscated a webpage before; when I check the source, if it's crap I don't keep reading. Which may be part of the point, here.
If it were to be done that might be the only way to do it. The author is going to have a better idea of what they feel is the meat and potatoes than I would.
