I have also been considering a mechanical keyboard, and likely my next keyboard will be such, although I'm finding hard time justifying getting one as long as this current bulk keyboard is working. However, cheap and mechanical is not a combination I'm so sure of. If you go to a store and test them, the noise they make is really spectacular. That's why I'd be likely to go not for the cheapest but the mid-range ones that can have some sort of noise dampening. Plus I'd choose switches without the intentional click sound.

I used to scoff at Bill's backlighting, but I have turned my coat on that subject and think it might actually be a useful feature. Lots of mechnical keyboards have no extra keys and the media keys, if present, are behind Fn. Of course there are exceptions like the Logitech G710+, which boasts a bunch of extra keys, like you'd expect from Logitech. Although to use the macro keys, you'd need Logitech's bloatware.

In short, I can't give you any suggestions, since I haven't been looking at the keyboards with the mind of an acute buyer. I have just read reviews here and there out of academic interest.