In a way there are and aren't "complete Gasket Sets"
As Six3jag, said, the complete gasket sets advertised do not include Seals.
You can buy a "complete Seal kit, but they don't include carburetor seals, alternator cover seals, etc....
There isn't a big master set that includes every gasket and seal on the bike....
This is true for most motorcycle seal kits, at least the ones I am familiar with.
The word complete usually means that it has the bottom case, cylinder, and head gaskets.
There are Top end gasket kits, that only have the head gasket and associated gaskets on the top of the engine.
And some gasket kits that only include the paper gaskets.
So read the ads and look at the pictures closely.
I couldn't tell you which of the 350 gasket kits is best... I have seen complaints and praise on all the brands out there.
The three I see the most are Vesrah, K & L, and Athena.
I have ordered paper gaskets only, from "The Gasket King" that were well made. But GK doesn't have the rubber or hard gaskets like the head gasket, only the paper gaskets for the side cases, etc....