In the case of the former, if your need is some light weeding once a week, then you can get away with a much cheaper, less robust, disposable battery-based trimmer to tend to your growth.
However, if you’re more Bigfoot-esque in the ferocity with which your hair grows in, you may want to spend that bit extra on a more durable, well-made trimmer that can be recharged via USB to save on battery costs in the long term.
When it comes to the latter question, nose hair trimmers generally can cost you anywhere from a fiver up to around £100 for the top-end options.