Quoted from PACMAN:A lot of SW assembly pieces are "NOT IN STOCK" on every site I've looked. I think they initially had some NOS parts but over the years sold out. There's really not very much reproduction DE Star Wars stuff out there either.
As for the speaker grills, those were screen printed directly to metal, not an easy thing to do and you'd have to get a lot made to make it worth it.
Hopefully your R2D2 body is in good shape because it is impossible to find. Mine is not and missing a side so not only are all the R2 functions currently disabled but the head also sits super low and looks terrible. Takes a lot of fun out of the game.