A few years ago we drove from western Iowa to Washington, DC. We took I80 out and we spent $49.00 on tolls and $42.00 on gas for my wife's Prius. On the way home we dropped south to I70 and spent almost nothing on tolls, the little we did spend was just getting out of DC. On the way out we tried to purchase a E-ZPass transponder, but we were told that there was no such thing as an "instant purchase" and that it had to be ordered and mailed to us. I think tolls are about half price with the E-ZPass.
Here, west of the Mississippi tolls are not typical, other then the Kansas Turnpike which I think is funded solely with tolls......no tax dollars are used.
After the trip east I felt like the state of Iowa should charge every car with plates from eastern states that have toll roads $25 or $50 to use our interstate system.:)