To the OP 2018 gear is testing and dropping at the mo so you can probably find 2017 on 25-30% off brand new, and then even 2016 gear brand new even less. I would go new and be consistent with the brand, don't be mixing and matching with kites.
I picked up kit as I went and mixed a lot of kites and then went onto a single brand. I would swear clear of high wind kites and edge towards a 9/10 12/14m kites. As a beginner going on when it's nuking will put the shit up you. So 13/15 knots, easy sessions, controllable winds will keep you in the sport, good luck