2000 Toyota Camry How much should it cost to replace a cata

I thought my son's '00 Camary just needed a new muffler. Instead I was told it was not the muffler that needed to be replaced, but the flex pipe and catalytic converter. My original quote was for around $500.00 at a local garage. Now I am told that the part needed is for a Camary that was assembled in Japan i.E. My son's and the new estimate, to repair is closer to $625.00 or $630.00. Midas quoted almost a $1000.00 for the job. How much should it cost?