So, if I wanted a sub $200 scanner with oil service reset for my fleet (see sig, but mostly for 2009 Cayenne and 1998 Boxster), which one should I get?

I just ordered this one.. For $12.00 I'll just keep it in my glove box
https://www.amazon.com/gp/product/B01C3HAHCS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

It seems like needing a scanner to reset the brake caliper piston is a bit of a myth.

The electronic parking brake manually actuates the rear caliper pistons. This means that, once removed, you cannot simply press or rotate the piston back into place. While many say that an expensive scan tool is necessary to complete a simple brake job, it’s simply not true. All you need are some Torx sockets, which you should already have in your toolbox if you work on your own BMW.

With the caliper removed, carefully rotate it (without twisting or pulling the brake line or power cable) so that you have clear access to the back of the electric motor. There, you’ll find two T30 Torx bolts. Use a wire brush to clean any rust out of these bolts so that you don’t accidentally strip them, and make sure that the socket is securely inserted before attempting to loosen them.

Loosen those two bolts, and the motor should come right off. You can suspend it like you did with the caliper itself, or carefully disconnect the power cable and set it aside. Be gentle when removing the motor, sliding it back and forth to loosen it so that you don’t tear the O-ring seal inside.

With the electric motor removed, you’ll be able to see where the motor interfaces with the caliper. Using either a triple-square socket or a T45 Torx, you can slowly rotate the socket clockwise by hand to retract the electronic parking brake.

From here, you can use a standard piston compressor tool to close the piston. Re-install the electric motor, being careful not to tear or pinch the O-ring, and you can now complete your brake job in much the same way as you did up front. Remember to re-connect the electric motors if you disconnected them.

https://bimmerlife.com/2019/07/20/diy-brake-jobs-and-the-electronic-parking-brake/

Not so easy.
<iframe width="560" height="315" src="https://www.youtube.com/embed/cHJMI4QkSy8" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

That is what I had to do on my wife's XC60. I'm sure the scanner is faster, I had to get one to do her transmission oil change.

What's the smaller Autel been up to?

This is the one I have. Looks like it's more than tripled in price since I bought it a few years ago.

https://www.amazon.com/ANCEL-AD310-Enhanced-Universal-Diagnostic/dp/B01G5EA74I/ref=sr_1_5?crid=26JST34DKNFXF&dchild=1&keywords=ob d2+scanner&qid=1601842037&refinements=p_89%3AANCEL &rnid=2528832011&sprefix=obd%2Caps%2C210&sr=8-5

That's a good value. I have an Actron like that. I got it for cheap last year as it was the parts store's scanner for customers and they stopped doing that for a while.

I like it because it provides live data like fuel trims and O2 sensor output. The bare bones one does not.

It's never been priced lower than $26.
No chance you paid $10 for this.
You're confused.

https://camelcamelcamel.com/product/B01G5EA74I

I was going to offer it up here, but the first time I mentioned selling it , one of my customers grabbed it up .

That's my recollection of something that I picked up years ago on a whim because the price seemed ridiculously low. Probably not 100% accurate. That said, I'm not sure how a website could accurately capture all of the prices paid for a product when Amazon (and many of its sellers) often use what can be described as an "airline pricing" model--where each customer is offered a different price at a different point in time in an effort to both entice them to buy and to extract the most money possible out of them. What I'm saying is that website can only see the prices that its bot was offered when it crawled the website, not the prices other customers were offered.

They use data from customer browser plug in. And direct searches from their site. That's how people use the service.

You can look in your Amazon order history to find the invoice price paid. Let's see how good your memory is !

Looks like I paid $28 bucks for it. And that was 3½ years ago. So I guess my memory isn't so good. The reason I thought $10 is that I frequently have something that I need to order and alway seem to be about $10 short of the free shipping (I don't do Prime).