I am considering geting an auto gps system and was wondering if there is a monthly cost, and how accurate they are on giving directions?

How is it that civilians are offered GPS service at no cost? I understand that it is being provided by the government. Is it paid for by tax money which would allow the general public to have access to GPS service? Will it ever be privatized such that companies will start charging consumers to have access to GPS signals?

I am looking for a mobile handheld gps device that has the capability to enter or type in an address of a residence or street address and then it takes me street by street to that address. Please help me by giving me the name of the gps device so I can look at it. Thanks.