Yes, door to door Kirby sales companies work much in the same way as car dealerships. They mark up the prices on purpose to pad the company's profit margin. A Kirby does not actually cost $2,000, $3,000 or whatever arbitrary numbers people are getting conned out of them for. The MSRP from Kirby is just a tad over $1,000, like vaclab posted from an actual retal sell-through model. Kirby has to get back what it cost them to make it, which only increases as time goes on because Kirby uses so much metal and slag casting in an era of Chinese plastic and vaccu-forming. Now it seems like a lot even at that price, but consider it will last the rest of your life, it is not a bad deal. Even those $700 Mieles love to clog up at the base due to the extreme angles of the airpath. I mean people pay that much more for a BBQ grill just to toss it out 2 years later.
The prices people are paying at door to door sales are what the DEALER is making profit on because they already paid money out of their pocket to lease the vacuums out from Kirby on the condition of a verified sale and payment from the customer. They more than double the price of the vacuum in order to cover the cost to buy more Kirbys from Kirby so they can sell more and make more money. It's an ongoing looping cycle.
So because of the pressure to make sales, they have to push hard and get mean to get those vacuums sold or else they can't make the sale and get the money back. The person doing the actual sales also gets a cut too, but only if they sell one. A lot of times they will not bother and just file the serial number off and take it to a pawn shop and pawn it off and say they sold it. That's how pawn shops get full of brand new Kirbys so soon after they come out. I seen an Avalir 2 at my local cash 'n' pawn in the 'hood for $150 but someone marked out the model tag with a sharpie and it looked like they took some car keys and destroyed the serial number. It also somehow had gotten so filthy even though these just came out fairly recently. I wanted it so badly but I didn't want to risk buying it and having my name attached to the sales records for it, even though it would probably be the pawn shop that would get in trouble if Kirby ever found out.
But yeah, dodes for controlling motor speed is pretty commonplace, it's the issue of what diodes they use and if they put in good ones that can take more capacity than they are rated for and still function safely. I have a Sunpentown vacuum that has a variable motor speed controller that is not unlike the dimmer knob on a light switch, and you can wind the motor way down to just a putter and it still runs, I don't know how, but it does. Pretty much all the vacuums were recalled years ago and they self-destructed on their own due to the motors overheating and erupting in flames and catching the plastic inside the vacuum on fire (hmm I wonder why)