Buy rebuilt 727 or get it done myself?

I'm so tired of hearing about, "Good quality complete rebuild kits"....they do not exist anywhere...Somebody thinks there are "no risks" in having a transmission rebuilt? AND others are recommending installing a used trans, then removing it and trying to get it backed up with a warranty, when the cost of the trans is half what shops charge to R&R a trans? You need to realize, first of all, that you are entering into a complicated endeavor. Step #1: What is the PK number on the trans? Good, now we're about 1/1000 of the way there.