Yep, you are right. $700 for the swap would mean an awful lot of free parts and building stuff yourself. Can't say it is impossible, but I know I don't get that lucky.
I am at $2845.24 right now, and I started with a $400 core motor. If the motor doesn't clean up, it will certainly get more expensive. But so far (I think) I am only missing a TC cover, water pump, balancer and gaskets. I've got the motor, 6.4 intake/injectors, 6.4 cam and the needed springs, headers, mounts, oil pan, oil filter adapter, wiring harnesses and PCM. It will certainly be higher, but I still think it will be below the $4K threshold. Oh, and I already have my fuel tank setup as well.
I will be the first to admit that I don't know what I don't know. Wish there were some others that could see that as well.