I'm thinking of getting a biomechanical tatto on my ankle/ foot just like the one in this picture http://www.emphasa.com/wp-content/uploads/2010/11/3D_Biomechanical_Tattoos__16_.jpg and was wondering how much something like that would cost
We really cannot give you an accurate answer.
You would be much better off, finding a tattoo artist (professional), and asking them.
It depends on time spent doing the tattoo, the artist, and this means the amount of detail and size factors in.
Most charge a minimum of $50 – $75 for under 1 hr = usually a simple small design
and then an hourly rate of $ 100 – $150 = this is estimated and then a price is agreed upon before any work is done.
You then sign this agreement, and you cannot be charged more than this, unless the design is added to with additional work.
You also should factor in a tip of 15% – 20%
So, a very rough guess for your example picture would be $200 – $400