Corsair K90 is a good keyboard, but the fact that it's only semi-mechanical makes it fairly sub-par (especially with the price considered). Unless you really find the lack of LEDs or macro keys a deal breaker the K60 is probably the smarter choice, although it suffers from the same shortcomings.
The K90 in short:
- A large bezel that messes with posture; due to it's size you will find your mouse area limited in space compared to a 'traditional' keyboard. It's simply too big.
- Membrane keys on ESC, F1-12, delete, insert, etc as well as the macro keys over to the left.
- Macro keys are on a separate, plastic bezel and sunk into the board. It makes them feel and look like an afterthought.
- There's simply too many macro keys. 18 (x3) in total. I don't think anyone need that many.
I would personally instead recommend a tenkeyless board. It will be within your budget (less switches = lower price) and make for a nice browsing and gaming experience since it provides a nice posture from the get-go with the space between your hands being close to the same as the distance between your shoulders (less neck and shoulder ache after long sessions).
Many brands offer tenkeyless boards. I personally have a Filco and a CM Storm, and while the Filco offers a much sturdier bezel, better plastic and overall a better experience the CM Storm line is not far off - and for ~$75 they are excellent.
I can also recommend the previously mentioned Qpad boards, Ducky Shine series, Das Keyboard and so on, although I don't see them being within your budget range. I can't recommend the BlackWidow, although the 2013 iteration solved some of the issues with this particular product. It's still a low-end mechanical board compared to the competition. I'd also be wary of the Logitech G710+. Not because it's bad, but because it's fairly new and still, to an extent, has a slight price premium. (In comparison, I think the K90 was around ~1499 SEK when I first scouted for it and now can be picked up for ~899 SEK.)
I'm looking to purchase the Razer Black Widow 2013 Tournament Edition because it is one of the cheaper mechanical keyboards where I am and I like that it doesn't have a numpad. Anyone owners have comments about the black widow keyboards?