The glass nail files are affordable, with prices starting as low as $5, and the standard size fits easily inside your purse. Or if you would rather keep one inside of your clutch or wallet they sell 'mini' glass files too. They are meant to last forever, so you won't need to worry about replacements.
My sister was actually the first person to introduce glass nail files to me. I had never heard of them before and thought it sounded kind of funny, but I looked them up and tried one and I was convinced I would never use any other nail file again. Not only are they amazing for filing and shaping your nails, they are better for your nails too and they look a lot better and last a lot longer then other cardboard nail files.
Be aware that there are cheaper replicas and you should avoid them, they are not designed, or manufactured as well and will break easily and hurt your nails!
I highly suggest you check out the glass nail files from design-glassware.com. Especially if you are someone that has weak or brittle nails, over time you may find a difference using glass nail files, plus they are more durable and cleaner too.
*I was compensated for writing this post, all opinions stated above are 100% my own.*