The example you put in the first post is very very simple 2D design that probably anyone is able to pull off rather quickly. Color palette is pretty unfortunate too. It's not my intention to bitch around, but tbh I wouldn't hire you because the first post doesn't show me the quality I would pay for. Maybe it would be better to put a link to a broader portfolio to convince us easier? General illustrations/designs not game related, different styles, different games with different moods, characters, complex vs minimal, etc. I think that would convince many more to hire you for their own games. By they way, there are other offering their services, one of them is Mike Wazowski from Monsters Inc (aka @VectologyGames) and maybe if you are lucky and want some isometric stuff @Walid, then @swiftcurrent might be your guy. Putting those two as an example so you get an idea of what the competition is offering.
As @Christoph said, Also you can get free game assets and graphics for free with the same quality graphics, or even better. But i like willingness, but i personally wouldn't pay for them. there ok, but not money worthy.
