A turntable is tricky to package so that it doesn't suffer any damage during shipping. Most new eBay sellers do not want to do a good job, because materials cost more than they think they need to spend.
Here's a webpage that shows how to pack a turntable:http://www.magma.ca/~jimrick1/PackingTT.htm
Instead of styro chips, I use 2" thick insulation board. Styro chips will work, insulation board will work even better.
The platter probably just sits on the spindle. It may be difficult to lift off if the spindle has a taper. Lift up on the platter with one hand, and gently strike the spindle with a rubber mallet to loosen the platter.
Good luck with your auction!