Isabella,
In Sydney I buy a brand called "So Gentle" at IGA supermarkets. It's in a small packet, just a bit bigger than the purse size Kleenex packets, so it won't jump out at you on the shelf -- just slowly browse through all the washing detergent products and I'm sure you will find a colour catcher of some brand there. There are 10 sheets in a pack, and I use a sheet 2-3 times each, not the once it says on the packet. It's good for normal clothes washing, to catch any loose dyes/ colours, especially if you are mixing darks with lights as I do all the time since I am washing for only 2 people.
If I was washing a quilt I would only use a brand new sheet.

It looks like a softener sheet. It comes in a small box about 6in by 6in. Mine is labeled Shout, but I know there are other brands. If you have them, they may be not be called color catchers , but somewhere on the box, they will be described as a product that absorbs any dyes that come off fabric in the washing machine and prevent those dyes from being re-absorbed into the clothing or fabrics that are in the washing machine. I hope this explanation is cleaRER than mud!

I also use mine until they have a bit of color on them.

I use mine until there is color on them.

I use the ones like dryer sheets but only once.

When I have several loads to do because the colors are too different to wash together, I wash the lighter load with a color catcher, then the next darker using the same sheet, and so on til I get to the darkest still using the same sheet then I throw it away. It is usually still pretty white, but I figure it's done it's job.