I'm 74kg and ride a 11mt 2014 Switchblade as my general kite and am happy with the size although I could have got away with a 10, but the point I'm making is your quite a bit heavier and you're looking at the same size kite. There is obviously a lot more factors that determines the correct kite size for an individual but rather than me rehashing them here's a previous post about the subject.
www.seabreeze.com.au/forums/Kitesurfing/Newbies-Tips-Tricks/Need-help-with-kite-sizing/ A good tip I got when purchasing my first kit was; go down to your local kiting beach and ask the guys, I'm sure they will be happy to give you some local advice. But be prepared to get some slightly different feedback, so then it's up to you so do your own research as well.
With regards to the price, I think there's a bit more negotiating to be done with that deal.
Good luck
Edit: I'm not saying an 11 is the wrong size for you but I'd do some more research.