New or Custom Hub Caps

You could paint yours....

 

You said "hubcaps", actually, wheel covers. But I take it you meant the rims?
Either way, less expensive to paint them.

I've watch videos of they using body filler after cleaning them.

 

Yeah hubcaps traditionally meant the caps on the hub openings, the small diameter holes in the centre of rims. Then popular usage shifted the terms to wheel covers, plastic faux-wheels, sometimes complete with faux-lug-nuts.

the alloy rims underneath were silver for 2010~2011, then black from 2012 onwards.

My first thought when I saw those black rims, was that Toyota was dismayed by the numbers of owners removing the wheel covers and adding centre caps (again, what hub caps traditionally meant), and they went to black painted rims in an attempt to dissuade the practice.

But owners continued to remove the covers, add centre caps, and black rims went from ghetto to chic.

If you’re set on wheel covers, I’d do some Bondo and sanding of what you’ve got, then sprayed them. Tastes vary, but consider just restoring them to stock; that colour is apparently Toyota’s Classic Silver Metallic (1F7).

 

Try ebay. You can find used OEM covers or knock-offs for your wheel.

 

May be ok. Buy from a local store, and see if they’ll let you return if not compatible. Avoid anything with metal jaws that’ll gouge your rims. From the description sounds like plastic jaws and a steel ring pushing them outward, which is ok.

 

I'm not sure, you'll have to ask them if they work on a Prius.
Ebay, as Merkey said, would be a good place.