Can anyone reccomend me a cheap GPS unit without a map/navigation?

I am planning on walking for around 50 days this summer in the Norwegian mountains and I’m looking for a cheap GPS unit that can tell me where I am in case I get lost. I am going to navigate with paper maps, but I want a unit that can give me the coordinates of my location. I don’t want a fancy big device with a big screen, simply because it’s expencive and I doubt that the battery will last. Does anyone have experiences with units like this?