HitLights LED Driver and Dimmer Switch in One 60W, 120V AC to 12V DC, Compatible with Most Solid Color 12V Strip Tape Lights, UL Listed, Single-Pole/3-Way, EZDim Pro, White

You can't (legally, or safely) have line-voltage connections flopping around outside of a junction box. Idk what you think is "very expensive" but Hitlights makes a 12V/60W integrated dimmer/driver that you can get for $100 which seems very reasonable over the cost of individual components: https://www.amazon.com/HitLights-Driver-Dimmer-Compatible-Single-Pole/dp/B0F9FMYWGQ/ The integrated dimming is a bonus if you want that, which would incur additional costs otherwise. Disclaimer: I have no personal experience with the product.