Almost all of them are free, BUT, they have premium versions that once you get the free one you'll realize how limited is and this will want you to buy the premium version...it's sort of like tourist trap! So really the only one that is truly free is still the Google one, and it's not that bad, but you have to follow it instead of it following you, having said that I use it exclusively and haven't had any issues, however when I start touring it may no longer be as useful and I'll have to buy a Wahoo Element Bolt or the Garmin Etrex 20 (because it has a much longer battery life and it uses AA batteries which I can carry spares). With the Etrex I can download Adventure Cycling maps into it, not sure about the Wahoo. But I haven't fully decided on the Garmin either because I might instead stay with Google Maps on my phone and use the paper version of Adventure Cycling so I don't have to worry about keeping two things charged, so if one were to die I would still have the paper map, either way I have learned that regardless what you use electronically it's wise to have paper map as a backup because this GPS navigation stuff isn't always right. Hopefully by the time I get ready to do that that batteries will improve a lot, and so will small solar rechargers, and doing a dynamo hub is even more expensive not to mention the slight friction. Etrex 20 is also a bit cheaper than the Wahoo.
There is a free app called Waze Traffic, it's available for IPhone and Android, it knows where you're at all times, it looks like Google Maps but you can navigate from one place to another. It does NOT show bike paths like regular Google shows, so if you're on a bike path and trying to figure out which way to go just flip between Waze and Google maps, a bit confusing but it does work with some effort, but don't forget...it's free!
I think if you want a reliable turn by turn cycling navigation system you'll need to buy one, unless someone mentions one here I don't know about.