RB20DET question

hey whats up guys i own a 91 240sx. i know i know, this is the skyline section. but that is why im here. the stock ka24de in my 240 just blew and i saw this as an oppurtunity to drop an sr20 in. everyone knows the sr20det is the ideal swap engine for a 240. upon my search for the SR, i found an RB20DET on the same website for $1500. the sr20 redtop on that site was $1800. is it just me, or is there something wrong with this picture? i hear the rb20 puts out about 214hp stock, whereas the sr20 pumps about 205hp. i just dont understand how a skyline motor (even though it is out of an R32) is $300 less than an SR? i can provide the link if you need proof. this is more of a skyline question so i thought id post my question here. thanks alot for your time and help guys, any help will be appreciated.