Uh so what you should do is *ASK* your professor *DIRECTLY*.
Also if I had an advisor that simply "dropped hints" that he doesn't have funding for me, I'd strongly consider changing advisors. Esp in an ECE program... and esp in a top 5 school. I know econ times are tough or whatever but profs not being able to support their own students is inexcusable. And then 'dropping hints' is even worse. You need to talk to him. Not just to figure out how bad the situation is but also to figure out if this guy is responsible enough to have grad students & whether your research area(s) generate so little interest that this could continue to be problematic in the future. PhD students have enough to do without having to worry about funding too.
But to answer your question, you could look into fellowship opportunities (though you're pretty much too late for any of the big name ones). TAing is also a possibility. You should again talk to your advisor about how that works at your school--in particular, if there are many more ppl wanting TAships than TA positions available, you need to get your advisor's aid to maximize your chances. You can also talk to some kind of more administrative position--department head, dean of engineering or whatnot. Unless your school is collectively an asshole, there should be resources to help make sure that PhD students have funding.
If all that falls through, then you have to pay. I would never pay for an engineering/science graduate program. That's laughably stupid.
Edit: you're international? Ouch. And you'd have to TA unpaid? Double ouch. On the former, see if your home country has any fellowship opportunities for students studying abroad. If you did your undergrad at home, contact profs/administrators there to see if they know of any programs that can help you. On the latter, you need to verify whether this is the case. They (=school) might be willing to let you do TA for pay if that's the difference btwn being funded & unfunded. Investigate. And again, talk to your advisor.