That is going to be a very tall order. PS/2 is getting rare and the only places you will find them normally are more industrial uses, since those areas tend to hold on to hardware more than others, and they will charge a lot. I found one but it was $375 bucks. Not worth it at all.
You could try a USB and use a PS/2 to USB adapter but that is probably not what you are looking for.
Thanks for the help, Jimmysmitty and Mandark. Yes, it isn't looking like illuminated PS/2 KBs are very readily available. Non-illuminated PS/2 KBs are aplenty, tho. I've found lots of them.
I did find this Corn Q500 that is illuminated, but was hesitant not knowing if it was truly PS/2 or simply came with a USB to PS/2 adapter. The details seem to indicate that the board has an actual PS/2 connector. What do you guys think?