in states with good public universities, the best value is 2 years at a good community college, then 2 years at the state school. even 2 years at a good state university is getting ridiculously expensive ($60K+).
From others experience it's 2 years at good community college and 2.5-3 years at the good state university. I've yet to see state college take all the credits from a transfer.
admittedly i don't have first-hand experience in this, but my understanding from friends & family here in CA is that limiting time at a state university to 2 years (and sometimes less) is entirely possible, with some planning.
the confounding factor for young adults, i suppose, is that it's hard to be certain enough about future interests amid all the possibilities not yet forgone to stay the course without (understandable) alteration (i changed course a few times in college myself).
UIUC is 25k a year just tuition and fees. Expensive college town room & board plus opportunity cost of education instead of working easily gets you to 30k a year.
Certainly not an option for everyone, but a ton of people in my state school class still lived at home. A good percentage could have lived at home but chose not to.
It's also hard for me to include housing because you'd need housing no matter what path in life you choose.