It is more than possible to just specialise in collecting this set and the associated artist's sketches, die proofs, progressive proofs with or without corrections, plate proofs, colour samples, stamp-timbres cards etc. It would constitute a prize winning exhibit but would only be financially possible for a very few. You can see my $5 imperforate proof by clicking here.
The printer sample is in a combination of black and brown which is not as good as the actual stamp in black and violet.
Reference: The Stamps and Postal History of North Borneo part 3.
Lots and lots information on this set and others. If you need a copy, enquiries to the publications officer at the Sarawak Specialist Society.