That's very high considering that your car doesn't have a timing belt.
Your engine, be it 4 or 6 cylinder, uses a timing chain and if that needs replacement, then about $500-$600 should be more than enough----unless of course they are replacing other things like water pump, drive belts, new coolant, new hoses, blah blah. Then I could see it hitting $1000 bucks.
You need to talk to these mechanics and get some straight answers and a detailed estimate. Let us know at that time if we can be of more help.