I got my covers printed at uni', it's not super cheap, it cost me £10 for 25, but they're good quality, just remember to supply an uncompressed CYMK format.
For the on dvd "artwork" I cut out a stencil from a thin sheet of plastic and sprayed printable DVD-Rs with some paint through the stencil,
then used Ghiant fixative spray (recommended by Marc, got it at blankdiscshop.co.uk at the same time as the dvd cases) to give it a better finish and prevent the paint coming off.
I also bought a rotary cutter thing from Staples to slice the covers out neatly,
I'd suggest going to your local uni' or college and asking about it there, It's the best way I have found of getting 25-50 covers printed.
Panasonic SD9, Panasonic NVGS-75, Canon MV600i