If an Anovos replica is a little out of your price range, you can make your own TOS Star Trek costumes out of a turtleneck with almost no sewing for under $10.
Pick up a turtleneck for a couple of dollars at a 2nd hand shop. It’s not only cost-effective, it also makes your Star Trek costumes more eco-friendly. If you don’t want to make the patches for your Star Trek costumes, you can buy premade iron-on badges, but I found it quite a bit cheaper to just make your own. (If you embroider the badges for your Star Trek costumes as I did, they will twist, but once you glue them onto the shirt, they straighten right out).