I would 100% say buy one there. It might be way cheaper through the school and ensures that you have the same uniform as everyone else...it would
suck to take your own and then find out it was wrong somehow.
Not a gi, but my WuShu uniform for the school in China only cost $5 there for pants and shirt! Too bad it looked like a bowling shirt with a prisoner
serial number stenciled on the front. http://public.fotki.com/bucho-ky/2007/china/kung-fu/csc0259.html