I would love to hang a Plasma TV on my wall, but darn that $10,000 price tag! If you can part with the BIG bucks for a plasma TV, you better part with the small bucks for a quality studfinder. Under no circumstances should you hang this TV in the drywall. You might consider using drywall anchors, but given the investment, I would be looking for a structural hold.
Spend $20 on a stud finder. It will serve you for a long time, and might save you some Plasma heartbreak.