If you work on a Mac and have the money to spare, consider
buying Vellum.
But — like you, Katriena, I anticipated publishing several more books in the (somewhat) near future, and I have my beloved Baby MacBook Pro, so
I bought the Vellum Big - Pack.
Not exact matches
It seems a little involved as it uses a virtual Mac running
Vellum, and you have to pay for access, but it's only tens of dollars compared to thousands for
buying a Mac.
It's like
buying nice pens and
vellum paper thinking they will help you feel better about drawing.