I know thw post is about cheap indoor but some people my want high great outdoor cords that can eandle max load per channel. those dollar tree ones are 22awg and indoor only and most I have seen is no ground I like ading a grounding bar and grounding the whole thing. Because this controllers can be used on more then just christmas lights.
22awg can handle max 7 AMP load, each channel on (for example) LE can only handle max 4amp, so I would not expect any load issues with 22awg per channel. For most Christmas lights, there are only 2 wires and polarity is not an issue. If I was using my controllers to make motors and other gadgetry operate, then 3 prong and polarity is important.
Hay, that gives me an idea, I could sequence Vixen and use an Exprsss for the rotisserie motor on my Gill for cooking a ham to Christmas music. Heck I could have 16 Grills going at once!