You get what you pay for.
Moreover, even if you used them, you'd discover you'd have to tolerate countless interruptions with pop-up ads, a smaller screen to accommodate advertising banners in the margins, and usually slower access (which would really eat up your rationed time).
I opted for Juno's PAID access, about $10 per month for unlimited time, which is half the price of MSN's regular access and about a fourth of the cable TV deluxe access, and about the only difference is that, when commencing my session, I have to click past two advertisements, which takes about ten seconds. If the Juno paid access is not as fast as the more expensive ISPs, I must admit that my computer and my typing skills are not so sophisticated as to make that difference significant to me.
I also use Hotmail's free e-mail service, which has the distinct advantage of being accessible (by password) from any terminal I might use while traveling, and the drawback to that free service is being able to keep only about 100 messages at a time but for $13 per Year I upgraded to five times more storage.