The seadoosource.com kit I bought had EVERYTHING I needed. In particular it has the right needle/seat combo INCLUDED along with the base Mikuni kit.
The coolest thing about the kit is it has the stainless steel cap screws for the pump body and the diaphragm plates. The original philips head screws strip out during removal.
You can buy the Mikuni kits for $35 a carb elsewhere, but then you will have to piece part the needle/seat, intake gaskets and all that....probably end up paying more and still missing something you'll need.