Why are they called Callaway Knock-Off's. If they are made my Callaway then then are not Knock Offs. If they are made to look like Callaway then you are just buying Brand X Golf club.
You don't know what your getting and believe it or not, it could discourage your continuation with the game. When starting you need all the help available - you don't need $ 2000 Callaway, but you may not want $ 50 Northwestern's either.
Maybe a friend has some clubs you could borrow.
Looks don't make a golf club perform, it's the technical work that goes into the design, spec's matching, weighting etc.. You need to hit the ball correctly, but from there it's the club that does the work.. You wouldn't put rated Grade C tires on your Corvette. Think of yourself as a Corvette - and what you will be using to make the ball go..
Either way - It's a Great Game - Good Luck and Enjoy what ever you decide.