- Blue switches are the stereotypical ones, they click loudly and have a noticeable bump on the actuation point (where the keystroke registers). They have 50g of resistance, generally considered the best for typing purposes.
- Browns are essentially quieter blues, they dont click on the actuation point but still have the bump. 45g of resistance, they are considered an all-rounder keyswitch essentially being a compromise between Blue and Red.
- Red is a much more linear switch, you cant feel the actuation point as well Brown/Blue and they don't click. 45g of resistance, they are considered best for gaming as it allows (apparently) for much more rapid key-presses.
- Blacks are the heaviest of the common keyswitches, 60g of resistance and you feel the actuation point even less than Reds. TBH I don't know why you would buy a Black keyboard.
I personally use Brown switches, and are what I think would be best for an office environment.
Cheap mechanical keyboards arent really a thing, the closest you going to get to a good cheap one is Coolermaster's lower end keyboards.
Something like this would be the best you can get while still being close to your price-range
http://www.newegg.com/Product/Product.aspx?Item=N82E16823129003