I like .us also.
This is a decent name but it leaves too many other combinations open for confusion. ApartmentRent, ApartmentRentals, RentalApartments, RentApartments, etc . . .
I think for this name to really work one would have to secure most of the other combinations as well as misspellings.
$50-200 as is
a bit more if in set
p.s.
You are right that people are always looking [for apartments]. The two most searched for subjects at my local classified ads site are jobs and apartments.