weighting boat for first time.

So I just bought a SV-211 crossover and can't wakesurf without holding the rope and its getting annoying so I'm thinking fat sacs?

I was thinking this 725 lb bag
http://www.amazon.com/Wakeboard-Boat-Single-Launch-725lb/dp/B001T3YKIK/ref=sr_1_3?ie=UTF8&s=sporting-goods&qid=1243825100&sr=1-3
for $110 shipped

anyone know what pump i should get?
looks like the Uber Pump is the way to go?

trying to spend under $200 so keep that in mind for recommendations, then maybe i will spend more in the future.

Thanks for the help :-) !!!!!!