Former Hasbro employee and toy designer Aaron Archer has listed for sale on his site a small 32 page book of his artwork, of Transformers toys.
The product page doesn't say a lot about what is in it, but the sample pages suggests that it is just creative drawings of various Transformers toys, not his actual design sketches (which would be Hasbro property).
As such, the artwork would be all original since he left Hasbro, but if you are a fan of his artwork, or his Transformers work in general, this could be something interesting to add to your collection.

It is called "Aaron Archer's Art of Transforming ROBOTs Volume one B&W Edition", which suggests that he might be planning a colour edition, or even more volumes (I guess if this one is popular enough, more will be produced).

https://archermonster.com/shop/ols/p...one-bw-edition

It is us$20, and if he ships outside of America, take that into consideration as well.