I have a motor that requires 12 V and up to 5A to function. (Current depends on torque, the higher the torque the higher the current but maximum current the motor can take is 5 A).

What's the best way to provide the power required ?

I'm thinking of buying this http://imgur.com/lHWps20

Then cut and strip the end of the wire.
What do you think

 

Yep, that ought to do it.
You might also press an old (or new!) PC power supply into use. They have a high current (a lot more than 5A) 12V output.