So for starters, the chance of getting a used toy is basically nil unless you're specifically looking to buy that. It's literally more economical to throw them away.

As for the discount, that's what I like to call a black Friday deal. $30 today, $30 reduced from $120 tomorrow. They never sold it at that tag, they just say so because it makes people feel like they got a good price.

As for the price, you gotta remember the construction of these things. Two motors, 20cm of wire, and a Chinese bluetooth module, they cost maybe $1 to manufacture and wholesale prices are like $3 each for a lot of 500. Selling it at $30 is going to make bank and people will pay.

The price of toys has been pretty constant over the decades. I'm more of an engineer than an economist, but if I were to speculate I'd say they probably operated on a much tighter margin back in the day and that set the idealized price. Now that production is streamlined and online shopping means you don't have to run a physical store, the margin is huge but the ideal price hasn't changed because customers expect a dirt cheap product will be garbage.