Cheapest as per staticice, not the cheapest it has ever been.
If you want the non-extendable legs, the OG Pixi is cheaper at $27.96.
Another Pixi with the smartphone holder integrated is $39.96.
Pair it with this smartphone holder or the cheaper one.
There are lots of cheaper alternatives, but Manfrotto plastics have never failed me. :D
Thanks for the post and research OP.
For a cheaper alternative though check out the Ulanzi MT 08. Way cheaper (less than $20 shipped including phone holder) and is a decent product.