I think it depends on how matching you want them to be.
We're only buying for the groom, and asking the ushers to wear grey suits that we know they already have.
If you want them all to match, I would include your ushers/groomsmen - I always think of them as the groom's bridesmaids anyway!
But I don't think you need to buy for the Father of the Bride, as he isn't part of the groom's party.
Hope this helps! X