Project TUrntable: Isolation suggestions.....

Have an entry level Project that skips from time to time due to room vibrations(doors closing, walking in room,etc)...what would be the most cost effective way to correct this? Currently on an a/v stand? Would cork discs under the table feet work? Wall stand? Maybe an adjustment on the table itself?
My turntable sits on a Target wall mount shelf. Instead of the thin wood shelf that comes with it, I use a thick maplewood platform. You can purchase one used here on Audiogon for around $110. That should take care of the skipping problem.
Try a wall mounted shelf. not on the wall with the door though.