It's the idea that counts
Can i do it? The first one looks quite easy (inb4 i just dissed some Worldfamous artist

)
Take a (B/W i guess) picture and paint over it. Prolly took him days to come up with the idea and then he made it within a day

At least it looks like it.
Why don't you create something on your own/ with your band? There has to be at least one who can draw decent

remember - it's the idea that matters. Tons of artwork out there looks great but isn't exactly good from a technical point of view.
Try it, and if it doesn't work you can still pay an artist to do it for you.
Maybe even use a group picture as base, and work from there, like in the first pic.
Take picture, scan it in - add some filters and/or draw on it in PS, or, if you want it more organic

Paint on the pic itself and scan it in when you are done. Just play around a little.
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@CrimsonianKing needs a CD cover/artwork, i did remember your pictures and recommended you