i got a used 7mgte with 112k out of a crashed auto 90 supra from a junk yard in oregon over a year go. i paid 1150 shipped. with uncut harness and turbo. overall it was in dam good shape. it runs real stong to this day. i didn't really do mcuh to it other than a new clutch, some hoses, and, lines then dropped it in. it blew the hg in a couple months so i change it with a felpro hg and its been good ever since over 20k miles(i drive my supra A LOT). my advise if getting a used motor.
1. get it from a junk yard that is with in 6 hours away that way if anything comes up you can talk to them in person...also let them know that you will do this. and fuck that jdm shit if looking for a 7m. who knows that last time those motors ran.
2. make sure it has at least 3 month warrenty.
3. get out of the newest and lowest amount of mile car.
4. get a auto. less chance it has been beat on.
5. finally get it in there as fast as possible to make sure it doesn't knock. hg isn't shit as long as it doesn't trash the bearings.
edit: you can rebuild an engine pretty cheap if you do most the work. but you have to go to the machine shop and TELL them what you want done. the moment you ASK them your going to be in deep.