steering problem

I have a 2003 xterra 4x4 v6 I brought it in to the dealer for hard steering problem, they replaced the steering pump. the dealer also said that it's steering box is not functioning properly and needs new gear assembly. they quoted it at 1938.00 new and 800 used just for the part. I looked online and a steering box was 100 bucks from a salvage yard. Is the assembly a different item then the steering box. Is it really worth 800 dollars? thank you