GPS-32 with a self-scanned and calibrated by hand paper chart.
Paper charts can be inexpensively scanned in a copy shop.
And then using the digital map in GPS 32, it must be calibrated.
You must read the coordinates of two points on the chart
and enter in the provided by GPS-32 available mask.
In the included help the process is described in detail.
The geo-referencing, as it is called, is simple and so you get cheep
charts for your navigation.