It depends on what time of day it is. During rush hour, it's crazy expensive. In the middle of the night it's a few cents.
Yup, I use the new lanes on I-75 from top to bottom, on average it will save 10 minutes Southbound and 20-30 minutes northbound when I generally use them. Usually costs $1.55 SB, and $1.65 NB. Though I have seen the SB toll at $3.30, $4.20 and $5.00. I don't use it if it goes over $2