Scott -

Assuming you could get them (and you can, I'm sure HD carries them) -
where would you mount it? Were you thinking of cutting a notch out of
the light fixture? If that's the case, why not just get a GFI power
strip, plug your appliances into it, and then plug it into the light
fixture when needed?

Also - keep in mind that just because your light fixture has a grounded
outlet - that doesn't necessarily mean that the ground terminal is
actually hooked to anything....... if your house is over 35 years old
or so, I'd say it probably isn't.

Basically, you've got 2 options:

1) Hack something together and hope for the best.
2) Pay the $$ to do the job right (have a new outlet added and home run
to the electrical panel).

I know, I know - money is tight. But when you are lying in helpless
convulsions on the bathroom floor as 120V has it's way with you, or
perhaps your house catches fire due to faulty wiring - you will really
wish that you had spent the $$. Well, maybe for a few moments anyway.

Not trying to be an ass - but this is a basic lesson that many people
died learning.