If it's a V6, the quote is a little on the high side, since the plugs are standard resistor plugs. If its the V8, that sounds a bit okay-ish as the factory plugs for the V8 are Iridiums and I believe about $8-ish a plug at Dealer Pricing, labor is something like .5-ish for both I believe.
Dealer quote me $299 for plugs. I asked why and they told me they had to remove the exhaust manifold. I laughed, went home, and did it in 1 hour (first time). Next time it will probably take 30 minutes.