"part could cost up to $1k"

my car is 2000 camry.
i asked around the shops, at least 3, all said parts plus labor was about $400. i had it fixed was because the pipe was broken, but not sure the converter was bad or not. i am just afraid the mechnic put old parts or my original parts back without replace it.
my friends in dealer told me the part was $1800. i didnot understand why the difference is so big.