This is my personal feedback.
Each consultants (coders included) have different skills experience and price.
Some are very busy and some less busy.
Price will depend of what you want and when you want it. (may be also if you want a kind of warranty)
The other points are totally dependant of your discussion/negotiation with the person you want to hire and how he work.
I have some plan for a "Tiki Board" were people could post their request and Tiki Consultants can "grab and apply". Until it gets real (if) I suggest you talk directly to people.