Noogai
Still Just a Settler
If only Liz was ahead of you in tech than internet wouldn't get you much since 2 AIs need to know the tech. Sounds like all hammers/gold/food (rush buy/whip) should have gone to infantry/artillery or tanks/bombers - whatever you had tech for at the time. As soon as you saw her building SS parts (before you were obviously) this should have been the plan. If you have the commerce to have a tech lead on everyone else, with US that means you have units. Stopping research for 10-20 turns for this won't hurt you since you had a lead on everyone else. If you were going for SS victory capitulate Liz when possible and direct her research to non-SS techs.
It's tough not to be afraid to declare on an AI with a tech lead (i do it myself often) but really even if you only had infantry/artillery vs tanks/fighters/SAMs etc you will have no trouble as long as she doesn't bribe someone in on you. Just hit before mech infantry and you should be good. Also, like GG said on turn 1 of the war anyone that is willing to be bribed on her would lower the price a lot.
I'd replay it if i were you if you have a save around the time you started going for internet. Losing to SS is rough and you should give it another try throwing all resources into an army to take her out.
Probably I should have just declared on her and then try to bribe someone (later they fighting with each other so it was impossible), but I was too since I avoided war for the whole game. I had Modern Tanks when AI had regular infantry (dunno about Liz though..)

She was building casings, but so was everyone else who went for Rocketry and stuff when I was teching Computers. I bribed other people against each other, but somehow missed Liz and then it was too late..
Screenshot one turn before I loose (note I have gifted and traded for gold several techs, since it doesn't make difference at this point):
Spoiler :

And the last screenshot (not many turns away from launching full SS, though I knew I lost at the time Liz launched her):
Spoiler :
