Be aware that those Bunnings pants looks like the cheap yellow PVC ones we used to issue at work, and they are seriously horrible, even for walking around in - thick, heavy and totally impervious to anything (until they tear). So while they may well be waterproof they don't breath at all to they are like wearing clingwrap in a sauna - the sweat is likely to wash your shoes off your feet
I hated wearing them to walk around a work site in, never mind doing any real exercise in them.
They might be OK for the occasional gentle ride to the shops or short commute in the rain - maybe.
Unfortunately there is no free lunches with waterproof anything - thin, lightweight, waterproof (as opposed to mildly water-resistant) and cheap doesn't exist. Thin and lightweight and cheap isn't waterproof for anything more than a light shower. It is only once you get into the serious GoreTex (or similar) fabrics that you get solid waterproof capability AND some degree of breathability and that stuff is pretty expensive. I bought a MacPac Traverse rain jacket a couple of years ago that is very waterproof and nice and thin/light and has reasonable breathability (still not adequate for serious exercise IMO) and it was reduced from nearly $600 to $299 when I bought it (not for cycling).