I have this pump, the one without the built in battery. I purchased a 7mha battery and a 10 mha as backup. The 7mha works fine but will only pump about 6 kites. The batteries cost between $25 and $35.
The pump works fantastically. I built a sand filter using a Kurig coffee filter. Lately we have been kiting in air temperatures in the low 40s F. The goal in these temps is don't get cold before you get on the water so recently I don't even take the pump out of the trunk. Get dressed at home, drive to beach, park into the wind. And pump my kite in the shelter of my vehicle flip it attach the lines using a line manager and launch.
I've never owned another one but I can vouch for this one, been using it since spring now without any problems.
If I don't ever manually pump a kite again i'll be happy. What a waste of energy it is. Sweating in the cold is worse then sweating in warmth as you know....
Go for, you will not ever look back if you do.
Sincerely
Pete