That's pretty cool! I have not done any projects with high voltage yet, but when I do I may start with the bulb.
I work in the medical device industry where needles are common. Not sure where to buy them retail. Try calling your doctor, dentist, or veterinarian and tell him what you want it for.
You may want to use a valve or stopcock on the vacuum line so you can disconnect it from the pump after the cavity is pumped down. If you just pull out the needle, some air may leak in.