i am 16yrs old and 11-12 stone, and i am starting up landboarding. what kind of wing span and size kite to pull me along and launch me in the air do i need, and can i have a rough price please?

What you buy really does depend on your budget and what winds you want to fly in.
For a good all round kite that will pull you on a board I have a 3.6 Beamer, needs a bit of wind to get going but nothing over 15mph - they cost less than £150 with handles and lines.

If you want to spend more go for a Flexifoil Blade III - about £350 for a 4m - loads of vertical lift.

And if you haven't flown before, which it doesn't sound like you have anything bigger would be suicidal! :o

but before you get a board learn to fly on your feet!

BUY A FLYSURFER there expencife but for your age the saft of the kite is very impotant and flysurfers are by far the best kites in the world, on land or water