This is the case with incredible designs from Fiona Marchbank with GIMP (very known as Open source and free).
She is using GIMP version 2.8. When she needs Vector elements she draws with Inkscape (also an an Open Source vector graphics editor, with quite similar capabilities to Illustrator)
Fiona is a freelance illustrator and designer, from Leeds (UK). She studied illustration at the University of Westminster in London. She makes work for Comics and Magazines.
She was also chosen to show artworks in Exposé Book, quite a reference as Ballistic Publishing has a good eye to choose talented artists.
LadyQuest 3 – Future Bitch
LadyQuest 2 – Feral Femme
Exposé 10 – Ballistic Publishing
Digital Artist Magazine: Jan 2012
InFocus: Dec 2011
Ambika P3: Westminster Illustration Degree Show, June 2011
London Gallery West: Broadvision, the Art and Science of Looking, May 2011
Nolias Gallery: WIP, June 2010
London Gallery West: Westminster Illustration Interrim Show, April 2010
Fiona fancies to draw stories. Where possible she like to use the single image to get as much information across about the characters and setting as possible using visual cues.