Even though I said that I would like to become an illustrator, I'm also looking into a 3D modelling career. I like the idea of working freelance in both professions although it might be a good idea to get a good steady wage by working for a company first, making a name for myself and then becoming a freelancer.
It's a lot harder to find information on freelance modelling as I suppose there aren't as many 3D artists compared to illustrators in the world. However, the link below, although American, states the prices of doing 3D models as a freelance 3D modeller, and if they are correct, there can be a good amount of money in it for a freelancer.
As Dave mentioned in PPGI - Week 2, companies are more likely to go for a freelance modeller as they may charge more overall for what is being done, compared to an in-house modeller, but at the end of the modelling or game, they can be easily gotten rid of as its a sort of temporary contract that is set up between company and freelance 3D modeller.
Other ways for a freelance modeller to make money on the side is by creating models in their spare time and putting them up for sale on such websites like the one below. If its of high quality, and is wanted by people, then that could be a sort of steady wage at the end of the day.