If you want a slightly used, but functional unit, I have an older Garmin 430S that I used for one year. It has the Bizer chart in it for the lake.
https://www.garmin.com/en-US/p/8054/pn/010-00515-30
I have it rigged on a 'cigarette' lighter plug and only kept it as a backup device as I removed it from the boat that I had for only one year.
You're free to look at it and make an offer. I can demonstrate it as it's easy to plug in to any car or boat that has a 12V socket (they used to call these cigarette lighters sockets).