Can anyone out there tell me if it is easy to replace a LE bladder or do i pay the 50 bucks for a shop to do it

Who are going to charge you $50?
Have you tried Auswind/Airborne in Ozzie Park 9244 4446?
I'm sure Matt can help you if you brought a new bladder off them?
Otherwise it is easy, just fiddly. If its a C kite, this is how I do it, I'm sure the Flow SLE's are the same

Lay your kite out

open the ends and pull some old bladder out

use your kite lines and tie one line to each end

go to the middle, open the zip, put your hand in and pull the inflating/deflating valves through, then pull the whole bladder out through the zip opening making sure the kite lines are attached and going through your LE.

Take note of its shape and the way it came out. unattach the lines and attach to the new bladder.

This is where you will have people dis agree, I powder the new bladder up with baby powder to prevent kinks and to ease it through better. Up to you?

Having two people here helps. Get someone at one end of the LE to pull the kite line back through to guide the new bladder in. You guide it in your end at the zip. Now do it at the other end till the bladder is back in the LE. Push the valves back up into place.

The bladder will be hanging out a bit on the ends. Unattach the kite lines. Go back to the zip and put your hand back in and pull back in the slack of the end tips till they are flush with your LE tips. You should see where they attach with some velcro. Then tuck the tips back in place.

Zip back up, pump up slowly and carefully checking as you go.

Others may tell this long story differant or dis agree but I have done this to at least five Airush kites I've owned.
Good luck