I assume that for nail polish you do not need a large area. Also you do not need to print/display larger than an A4 sheet.
If that is true, then I suggest that you first use your kit lense at longest end (55mm if it is 18-55) and see if that suffices. Alternatively if you have a good cell phone - Apple or Nokia with a camera of 5MP or mode, that allows macro setting, use it to take the images. I have shot a lot of small objects with my 5MP Nokia and done properly they suffice.
Now compare both images and see if it solves you problem. If it does, well and good, else get the best macro lense you can afford. Just remember for static objects on a table top, shorter focal lengths will work, but for insects longer focal lengths are needed to keep a working distance from the insects.
Another thing that you might consider is upgrading the camera body. Upgrading from 10MP to 24Mp body will give you a tremendous boost in resolution, and the D3300 with its 18-55 kit lense will give you cleaner images. What higher resolution means for you is that you can shoot at lower magnification but blow the images up 60% more, so you get a larger image. In case you can sell off your current body with its kit lense, a new D3300 with the kit lense may cost you less than $400.
If that is true, then I suggest that you first use your kit lense at longest end (55mm if it is 18-55) and see if that suffices. Alternatively if you have a good cell phone - Apple or Nokia with a camera of 5MP or mode, that allows macro setting, use it to take the images. I have shot a lot of small objects with my 5MP Nokia and done properly they suffice.
Now compare both images and see if it solves you problem. If it does, well and good, else get the best macro lense you can afford. Just remember for static objects on a table top, shorter focal lengths will work, but for insects longer focal lengths are needed to keep a working distance from the insects.
Another thing that you might consider is upgrading the camera body. Upgrading from 10MP to 24Mp body will give you a tremendous boost in resolution, and the D3300 with its 18-55 kit lense will give you cleaner images. What higher resolution means for you is that you can shoot at lower magnification but blow the images up 60% more, so you get a larger image. In case you can sell off your current body with its kit lense, a new D3300 with the kit lense may cost you less than $400.