I've been reading about alot of people painting their lowers, my car is black so I'm not too concerned about it but I would still like to do it. The only thing I'm worried about is in a couple of months is the paint gonna start to crack. I can't imagine how good it will hold up on the surface of these. Anyone had any trouble with the look of theirs after they did this?

To have the paintwork done properly it should be done by a bodyshop that mixes their own paint. To paint plastics and rubbers (which both flex slightly) a "plasticisor" has to be added to the mix, this makes the paint flexable.
If this isn't added then the paint will in time crack and chip

Thanks, Now you say mixing their own paint. I figured I would probably get the paint straight from AUDI so it will match perfectly.

your not just thinking about applying the paint alone right? you got to sand and so a bunch of stuff before you can paint.

the paint from Audi will match but it won't have the plasticisor (sp) in it so when the plastic/ rubber you've sprayed on the car flexes slightly (it will flex otherwise the parts would probably be metal which doesn't need to flex) the paint will crack/ peel

as mentioned above you'll also need the parts de-greased to remove any silicones from polishes, rubbed down to help the paint key to the surface, primed (primer should have plastisisor in it as well), smoothed with wet/dry and this is before the paint goes on

i've sprayed quite a few plastic trim parts (smaller parts than yours), taken my time and never got totally unblemished finishes - it's worth paying a little more to get a bodyshop do it