Power supplies: are they just available to buy?

[Jason Coates]

I love building modules. I love making panels, and designing all that
sort of thing. I am also totally incapable of making a power supply.
What I want to know is if there exists a pre-assembled power supply that
has connections for + and - 15v, and 0v. (gnd) I don't want anything
fancier than that, just something I can buy and plug in and solder
modules to; but is such a thing out there? I'm assuming that, since it
would make my life much easier, it's miraculously not been thought of
yet; but I have to be wrong. Help!? =) Thanks-

	Jason