If you are thinking about buying a mechanical keyboard and want us to help you choose, format your post as follows.

>Budget
>Location (continent at least)
>Preferred switch type
>Layout
>Form factor
>Backlight
>Previous/current keyboards

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1) Budget
Mechanical keyboards aren't cheap. 
Stock prices start at around 70$ for cheaper boards (40$ if you want knockoff switches like Kailh) and can go over 250$. If you live in Europe add ~30$ to the price (+ possible customs and shipping costs).

2) Location
Availability of keyboards varies between continents, as do purchase possibilities.

3) Preffered switch type
There are plenty of switch guides and comparisons, take a look at this chart (http://i.imgur.com/5uKCsvv.png) or use a search engine of your choice. If you're not sure about a certain switch at least specify if you want tactile or linear, clicky or silent and hard or soft.

4) Layout
Mostly ISO or ANSI. Be aware of the fact that the selection of keyboards and especially aftermarket keycaps is far greater for ANSI.

5) Form factor
Specifies the amount of keys your keyboard will have:
- 100% - full keyboard with function keys, navigation section and numpad,
- 80% or TKL (tenkeyless) - usually without numpad, but there are also keyboards without arrows instead,
- 60% - no numpad, function and navigation keys are on a function layer.
- 65-75% - different variations of previously described.

6) Backlight
Do you want LEDs.

7) Previous/current keyboard
If you want something similar to your previous keyboard, or perhaps the exact opposite of that.