For cheap navigation I’d suggest the Etrex 20. Does most of what the 30 does, but cheaper. It’s really a hiking GPS but with all the basic cycle functions you need, speed, average, distance, etc. So good for different stuff. Quite bulky though. And buy a proper Garmin mount (and lanyard). They take AA batteries too, and last up to 25 hours, so good for long rides, touring, stuff like that.
The Edge units are very cycle specific. Loaded with loads of data and training functions, which you may or may not be interested in. But something with proper mapping gets relatively expensive. They’re much sleeker than the chunky Etrex though, both physically and…..softwareably, and easy to use on a day to day basis.
There’s the Touring too, which is reasonably priced, but I don’t know much about it.