its already balanced from the factory, so if youre just machining the face of it for a new clutch, theres no need to get it balanced.
if youre getting it machined ie: weight reduction, yes, itll need balancing, but you should really balance it along with the whole rotating assembly of the engine (optimally)
to get the face machined is only 20-30bucks
to have the whole rotating assembly balanced is around 160-180bucks