Why would you spend any money on obtaining a PhD? If you were given generous offers, then the PhD programs should be fully funded. The stipends are not large, but they do cover full tuition plus around $20k/year for living expenses. I'm not in history, but I'm a professor in another humanities field and what I generally tell my students is that a PhD is worth if it is something you love, you cant imagine doing anything else, and you do not go into debt for it. If you're not passionate about the discipline or teaching, that's another story though. In my program, we have about a 50% placement rate for new PhDs-- so there is a risk that you may not find an academic once you are finished. There is a similar risk in other fields too though.