I got BringGo and it has worked quite well for me, and in my opinion is very cheap nav at $60.
My wife's new Ford Escape has nav built into the vehicle and works great and is fast to set up each trip. BringGo on the other hand takes longer each time you get in the car as it first requires your phone to connect with MyLink, then a few seconds later for the BringGo app to enable on MyLink, and the button selections don't respond quite as fast as the Escape's built-in. As long as you give yourself a couple minutes to set up a trip, the map visuals are clean and attractive and the voice directions are pleasant and clearly audible. The appearance and feature-set are comparable to many built-in navis.
And if another family member drives the car, they can also get the app on their phone through your account at no extra cost; plus you then have navi you can run from your phone if you ride in someone else's car.
damn, I sound like an advertisement.
It may only be my experience but the only potential downside is the purchase and initial setup process can be somewhat tedious and confusing, at least it was for me; so pay careful attention and make note of the steps, and be sure to remember the login you applied to the app. You really only need to log into it the first time you use it, but if you ever actively log out of it, well... you know what I mean.