the $0.02 list and you didn't' specify what KIND of computer art you want to do, there are literally avenues that does exist for traditional artist that are commonplace on computers these days.
Free
Painting
GIMP
photoshop's counsin who lives in a Van by the side of the River. A favorite of game designers, texture artists and production houses on a budget.
3D
Blender
If learning curve is not a problem this product should require a helmet and a seatbelt, it will go toe-to-toe with Maya, Mudbox and anything else Autodesk puts out, just dont expect the rest of the 3D community to embrace you for using software that does not cost the same as a yearly car payment for a BWM, those guys are snobs. Blender is more of a 3D workhorse that will do what $3K software wil do and its freakishly stable and a constantly gets new features.
Daz Studio, a modeler for people who want to make human figures in scenes but has no interest in modeling. The base prodcut is free, the assets can cost a few dollars or more.
Not free
Affinty Designer
the only company who hates Adobe more than you. It's not PS but it's very clean. It's street name is "The Photoshop Killer", they also make an illustrator like product, both of which are about $40 to own - pay once, thats it.
Adobe Creative Cloud
starting to not be the only game in town, but they did not get the memo. Its now about $40 a month to 'rent', still the industry standard and if show up for a job as a graphic designer and the big three are not on your list (Photoshop, Illustrator, InDesing) expect your Resumé/Curriculum Verte to wind up in the trash/dust bin. I've been in the industry for years and watched it happen even when someone had in impressive portfolio. Not knowing it in the professional world is a deficit, unless you own your own production house and can make your own rules. It's like being in a grunge rock band and not owning an amp, or a guitar, and you wear dock-siders, khaki slacks and a Jimmy Buffer shirt - without the irony!
Corell Painter
More of a traditional art package, works wonders with a tablet. Substantial cost drop if you have a college or HS email account ending in .EDU
Autodesk
Autodesk makes a veritable slew of products, some of which are free to students and hobbyists but with substantial limitations. Full versions can be pricy and out of reach for anything outside a professional development company or a someone with a trust fund and a lot of time on their hands to learn it.
