battery terminal are tight, all lights (and indicators) work, fuel pump works...when I turn the key the headlight relay switch buzzes and all electric shuts down when I hit the starter switch

I can only bump start it.

Any ideas?

AHHHH, I may have the answer for you. I had a very similar problem with my Vegas awhile back. Try taking off your battery terminals and cleaning them with a wire brush. It sounds crazy but mine did the same thing. That is assuming that your battery isn't going dead. Good luck.