2011 Prius 2 - maintenance dealer wants to do over and above what the maintenance book calls for.

oh ya, lots of threads here on this kind of thing. stick to your guns, do some research here and ask questions, you'll get plenty of good advice. all the best!

 

If you plan to keep the car a long time, it's not unreasonable to replace the fluids in the the transmission and brake system. Neither procedure should be "very expensive," though. The transmission is a simple drain-and-refill routine, so don't let them over-complicate it. You can find scads of threads on the transmission oil change within PriusChat, including how to do it yourself.

 

Brake fluid change is in the Canadian maintenance schedule since 2014 model year (or even earlier). It's every 3 years or (something like) 48,000 km's.

Transaxle fluid change is worthwhile, particularly a first, early change. It's an ongoing head scratcher why Toyota insists it's not necessary. If it's crazy expensive what they're quoting to do this, not good: it's about the same complexity as an oil change, and the TOYOTA ATF WS around $10 per quart, 4 needed.

Both of the above should be around $100, maybe more for the brake and less for the transaxle.

 

I've responded to a lot of threads like these, and you're the first with a dealer who's only recommending reasonable items. I've done nearly every maintenance item myself on my 97K mi 2012, and here's what I think:
Engine Oil/Filter: I wish I'd done 5,000 mile intervals instead of 10,000 intervals. But no damage has occurred.

Transaxle Fluid: This is the most important after engine oil. Should not cost more than $100 USD. Takes about four quarts. My dealer wanted $325 and that's when I decided to do things myself. This is a change and not a flush. (Prius has no torque converter or any transmission lines which can be flushed!)

Brake Fluid DOES get old and it is reasonable to recommend a flush.

My throttle body had some varnish on it but nothing that could impede performance. Not an unreasonable recommendation at all, but mine didn't seem to need it.

I replaced my engine coolant and my separate inverter coolant. The fluids seemed extremely clean and didn't seem to need replacement, but the replacement was reasonable.

I suggest you ask the dealer to:
1) Engine oil/filter change
2) Transaxle oil change
3) Lubricate the brake caliper sliding pins (2 per wheel). Yes, it's important.
4) (Maybe) Brake fluid flush, if you can afford

I operate my vehicle in California. It's never been in snow or even freezing temperatures. Maybe where you live the temps are a little harder on the fluids.