Are you stirring a gel polish? If so, OPI makes a great stir stick. It's metal and has a large flat end and a small flat end. I just use that and stir by scraping the bottom and pulling up the pigments to the surface. I then just stir it as if I'm stirring cake icing from a can. Because of the flat head I can scrape the gel off it on the side of the pot without and waste. I'm sure a cocktail knife or plastic knife will work just as well, they may be cheaper . I paid $10 US for my OPI stir stick.
If its not gel polish you are stirring but regular gel, be careful cause over stirring will cause tiny bubbles in your gel and you will end up with a lot of pinhole dips on the enhancement after filing