I was planning a trip this summer, and wanted to get a GPS device to help me out. The last trip I took in February, I relied on a map I printed out and a compass. That wasn't easy. And it was hard to find specific locations because the map wasn't detailed enough. And sometimes I'd want to go south, look at my compass and it says I'm going south, then after going perfectly straight for a mile or two, the compass says I'm going north. I don't want to deal with that again, so I want to use a GPS. But I don't know anything about them. Do they require subscription fees? Is it a service I have to pay for monthly or yearly? Or do I buy the device and I get to use it for free as much as I want for as long as I want? Thanks.