Hi! I am starting the process of building my first quad. I can’t afford to buy all the parts outright (and too impatient to save!), so was thinking of buying the frame: http://www.unmannedtechshop.co.uk/i450a-quadcopter-frame-same-as-dji-f450.html to go with the kit: http://www.unmannedtechshop.co.uk/quadcopter-motor-esc-combo-kit.html with 850kv motors the 12" props and 22A ESC. Am I aiming in the right ball park?
With the 850kv motor the recommended prop is the 10x4.5 prop and 22A ESC, the 880kv motor you can go to 12x4.5 prop with a 30A esc.
However, the frame you have selected is suitable for up to 10" props so really your choice is limited to 850kv with 10x4.5 and 22A ESC.
As Luise said, its best to use 10inch props with the 850Kv motor.
But for a starter quad I would rather suggest you go for the MT2213 motors we sell, along with a 4in1 20A ESC. The motors come with a free set of props already so it saves you abit of money. We have some more of the MT2213 motors on the way and they should get here in about 2 weeks.
Cheers 
I have asked the website to tell me once the motors are back in stock 