I did buy aftermarket taillights for my Accord. They had a blackout look & had a sequenced bar for turn signals, very different from OEM. I did it because the look they provided was worth the risk of non-oem parts direct from China. I'd apply the same rules to the Tesla. If something different enough that I liked came along I'd do it. Given the cost of the car I probably would not if they looked the same.
you will always run the risk of a non-oem part being inferior to the OE version. taillights and headlights are especially known for issues with leakage, failed LEDs, etc. i would consider the cost savings vs. the headache should anything go wrong. if the discount is deep enough, it may be worth the risk. you're you're talking about $50, you may want to stick with OE.