Hobby tools, materials, and subject matter can be found in a variety of places. Your local hobby and game stores, big box arts and crafts stores, dollar stores, and believe it or not beauty supply stores! While I find my hobby supplies in a number of locations today I'm going to focus on what you can find in the beauty supply section of your local store.
Nail files are always a great buy. They come in various grits and sizes. These are far cheaper than those you would purchase at a model hobby store. The files are also better than loose sheets of sandpaper because the stiff board makes using it effectively far more easy. I would recommend supplementing your supply with some quality ultra fine grit sandpaper from a hobby store, but the bulk of your sanding can be satisfied with nail files.
The nail section is full of great finds, nail files, clippers, and even nail polish. That's right nail polish can be thinned down with laquer thinner and run through an air brush. Granted most of the colors you'll find are better suited for painting model cars over war game models but the option is always there.
Okay so cotton swabs aren't exactly new to the model hobbiest but I do suggest purchasing the ones from the beauty section. The cotton tends to be tighter bound and they even come in shaped pointed tips. I like to use my cotton swabs for cleaning up oil washes.
Makeup applicators are a cheap effective way to apply weathering powders. They can be purchased in small disposable versions like the ones that come in compacts or even longer handled versions allowing for better control and help getting into those hard to reach places. You may have even seen Tamiya's line of weathering powders which are essential eyeshadow compacts.
Makeup sponges can be used to apply weathering powders or tore into pieces and used to stipple colors for weathering or texture effects.
These are just a few of the great hobby supplies you can find the in the beauty section. Take a look around and you'll also find a wide selection of tweezers, and cuticle pushers are great for sculpting. Just remember to buy your own supplies and don't go raiding the beauty supplies of the ladies in your life, they may not be too pleased to find resin dust in their nail files.