*coughs*
Goddamn that is steep. Seriously. Maybe that's the new normal... and if so I need to change careers.
While an evacuator will get MORE fluid out - it will not get ALL of the fluid out. It simply cannot be done unless/until the car is run through gears and the torque converter is in motion. That being said - a lot of that fluid cannot be displaced (read: sent back to the pan) until there is new fluid being pushed in there to move it further down the line. Trying to suck it dry with the machine while doing the above will result in a shot trans and is not an action that any shop would ever do.
I have heard of a different kind of flush system that supplies fresh fluid while evacuating the old and being run through the gears - but those are bloody expensive machines and I have seen them few and far between. They are non-existent in every Hyundai, Honda and BMW shop I have ever set foot in. Most actual trans shops would opt to remove the trans, I think.
If you are ok with the cost - then go ahead.... but again - don't think you are getting a really thorough change - or a more thorough one than if you did it yourself... especially if you did it 3x.