a sd card got stuck inside the mac

This thread (long one) may contain some helpful advice.

https://discussions.apple.com/thread/2283444?start=0&tstart=0

If it's any comfort, it is a more common thing than you might think, what with the SD and CD slots being next to each other.

Please don't feel bad, lots of people have done this. Here is one reliable solution for getting it out:

http://www.youtube.com/watch?v=hpwDfpH4hR0

No they'd probably remove it for free. Have you tried lifting the machne and turning it on it's side to see if the card just falls out?

Give it a couple of good shakes while holding it, it may jar loose.

Popular successful techniques involve artfully folded business cards or the use of a Shop-Vac.

If you shake it around be sure the Mac is completely shut down.

Before carting the Mac to a technician, did you try the L-shaped piece of cardboard as shown in the video posted by rKaufmann87? It seems to work for most that try it.

The reason I like the business card or vacuum technique is that it would be difficult to break any mechanism inside the drive. Bent paper clips are more risky.

If this is an iMac, you'll have to upend it and make gravity work for you. Unplug everything and work over a forgiving surface.